The synaptic origins of receptive field properties in the cricket cercal sensory system

Summary The regional distribution of cerebral glucose utilization, revealed by the¹⁴C-2DG technique, was compared between (i) toads after stimulus-specific long-term habituation of the orienting response toward a repeatedly presented prey dummy (habituation group) and (ii) non-habituated toads, readily orienting toward the repetitively presented prey stimulus (naive group). In the habituation group, the ventral medial pallium (vMP), a certain portion of the preoptic area (PO), and the dorsal hypothalamus (dHYP) showed a statistically significantincrease in¹⁴C-2DG-uptake;decrease was observed in the ventral layers of the optic tectum (vOT), a portion of the tegmental reticular formation (RET), the ventral cerebellum (vCB), and the striatum (STR). The results suggest that stimulus-specific long-term habituation of prey-catching affects both, components of thestimulus-response mediating circuit (e.g., involving OT), and structures extrinsic to it, (e.g., vMP, PO, dHYP), which may belong to amodulatory circuitry. Bilateral lesions to vMP strongly delay habituation. Our results are suggesting that damping of the adequate behavioral motor response during habituation involves active inhibitory processes of a modulatory system that develops in strength during stimulus repetition so as to suppress response output, which basically supports Sokolov's hypothesis (1975).Abbreviations A anterior dorsal thalamic nucleus - AL amygdala, lateral portion - dCB dorsal half of the cerebellum - vCB ventral half of the cerebellum - DP dorsal pallium - dHYP dorsal hypothalamus - pLP posterior half of the lateral pallium - Lpd lateral postero-dorsal thalamus - Lpv lateral postero-ventral thalamus - aMP anterior third of the medial pallium - dMP dorsal portion of the posterior medial pallium - vMP ventral two-third of the posterior medial pallium - MS medial septum - dOT dorsal layers of the optic tectum - vOT ventral layers of the optic tectum - P posterior thalamic nucleus - PO preoptic area - RET tegmental portion of the medial reticular formation - STR striatum, dorsal and ventral portion - vTEG ventral tegmentum     

Conservation of the 3′-untranslated regions of calmodulin mRNAs in cetaceans

Three separate calmodulin (CaM) genes (I, II and III) encoding an identical CaM protein but differing in the 5- and 3-untranslated regions of each of the three mRNAs are present and highly conserved in all mammals (so far examined). Primers complementary to the 3- untranslated region (3UTR) of each of the three mRNAs occurring in human, rat and mouse were synthesized and used to amplify regions of the 3UTR from genomic DNA isolated from cetaceans, specifically from the bottled-nosed dolphin (Tursiops truncates), the pygmy sperm whale (Kogia breviceps) and the humpback whale (Megaptera novaeangliae). Using several primers and PCR conditions, the three CaM genes were identified in all three species by this method with one exception. The sequenced regions of the 3UTRs of the three genes of the cetaceans exhibited a high percentage identity when compared to the corresponding regions of these three CaM mRNAs isolated from humans (85-96%). These partial sequences of the 3UTR regions and the corresponding regions for humans, rats and mice that were available from the database were aligned and a phylogenetic tree was constructed. The three CaM genes from all species showed a close phylogenetic relationship based on these 3UTR sequences. Such high conservation of the 3UTRs suggests a specialized and significant function for this region in mammals.     

First Field Studies of an Endangered South African seahorse, Hippocampus capensis

South Africa's endemic Knysna seahorse, Hippocampus capensis Boulenger 1900, is a rare example of a marine fish listed as Endangered by the IUCN because of its limited range and habitat vulnerability. It is restricted to four estuaries on the southern coast of South Africa. This study reports on its biology in the Knysna and Swartvlei estuaries, both of which are experiencing heavy coastal development. We found that H. capensis was distributed heterogeneously throughout the Knysna Estuary, with a mean density of 0.0089m^–2 and an estimated total population of 89000 seahorses (95% confidence interval: 30000–148000). H. capensis was found most frequently in low density vegetation stands (20% cover) and grasping Zostera capensis. Seahorse density was not otherwise correlated with habitat type or depth. The size of the area in which any particular seahorse was resighted did not differ between males and females. Adult sex ratios were skewed in most transects, with more males than females, but were even on a 10 by 10m focal study grid. Only three juveniles were sighted during the study. Both sexes were reproductively active but no greeting or courtship behaviours were observed. Males on the focal study grid were longer than females, and had shorter heads and longer tails, but were similar in colouration and skin filamentation. The level of threat to H. capensis and our limited knowledge of its biology mean that further scientific study is urgently needed to assist in developing sound management practices.     

Antide B,an antagonist of LHRH with cis-3-(4-pyrazinylcarbonylaminocyclohexyl)alanine in position 5

Summary Several LHRH antagonists with trans-3-(4-pyrazinylcarbonylaminocyclohexyl)alanine (trans-PzACAla) in the position 5 were synthesized and their antiovulatory activity was compared with the activity of the analogs containing cis-PzACAla in this position. In all cases cis-isomer produced more potent analogs. Introduction of cis-PzACAla in the position 5 of Antide gave Antide B which completely inhibits ovulation at a dose of 0.5µg/rat. Antide B releases negligible histamine (ED₅₀ = 104µg/mL), and has excellent solubility in water. Also, an improved synthesis of cis-PzACAla is reported, involving the hydrogenation of 4-aminophenylalanine on a rhodium catalyst to give the desired cis-isomer with a 53% yield.Abbreviations Cpa 3-(4-chlorophenyl)alanine - ILys N-isopropyllysine - Nal 3-(2-naphthyl)alanine - NicLys N-nicotinoyllysine - Pal 3-(3-pyridyl)alanine - PicLys N-picolinoyllysine - PzACAla 3-(4-pyrazinylcarbonylaminocyclohexyl)alanine - Qal 3-(3-quinolyl)alanine     

Copper and cobalt uptake by metallophytes from Zaïre

Summary Pot trials were carried out on plants ofHaumaniastrum katangense, Haumaniastrum robertii andAeolanthus biformifolius. These metallophytes from Zaïre were grown in substrates containing from 0–10,000 g/g (0–1%) copper or cobalt. The tolerance of each species was determined and for cobalt was highest inH. robertii (4000 g/g) and for copper was highest inAeolanthus biformifolius (9000 g/g). Discontinuities in the plant-soil curves for each element indicate an exclusion mechanism operating for all three species at lower concentrations of the element in the soil. All species would grow in soils containing only traces of cobalt or copper and this indicated that uptake of heavy metals was not linked to a physiological requirement for either element. The plant-soil relationship for cobalt (P<0.001) was sufficiently good for all three species for them to be useful in biogeochemical prospecting for this element.     

NMR detection of side chain–side chain hydrogen bonding interactions in 13C/15N-labeled proteins

We describe the direct observation of side chain–side chain hydrogen bonding interactions in proteins with sensitivity-enhanced NMR spectroscopy. Specifically, the remote correlation between the guanidinium nitrogen ¹⁵N of arginine 71, which serves as the hydrogen donor, and the acceptor carboxylate carbon ¹³CO₂ of aspartate 100 in a 12 kDa protein, human FKBP12, is detected via the trans-hydrogen bond ^3h J _{N CO2} coupling by employing a novel HNCO-type experiment, soft CPD-HNCO. The ^3h J _{N CO2} coupling constant appears to be even smaller than the average value of backbone ^3h J _NC couplings, consistent with more extensive local dynamics in protein side chains. The identification of trans-hydrogen bond J-couplings between protein side chains should provide useful markers for monitoring hydrogen bonding interactions that contribute to the stability of protein folds, to alignments within enzyme active sites and to recognition events at macromolecular interfaces.     

Monoclonal antibodies as a tool for phylogenetic studies of major histocompatibility antigens and β 2-microglobulin

The cross-reactivity of several monoclonal antibodies recognizing monomorphic determinants of human HLA-A, B, C, and DR antigens and human 2-microglobulin (2m) has been studied on peripheral blood leukocytes in 24 different species. An monoclonal HLA-A-, B-, and C-specific antibody and four monoclonal HLA-DR-specific antibodies cross-reacted with cells from all the primate species tested. Furthermore, antibodies HLA-DR-specific were positive with peripheral blood leukocytes (PBL) from cows, goats, sheep, horses, and dogs. Two monoclonal 2m-specific antibodies, which were positive with PBL from certain primates, also reacted with cells from cows, goats, sheep, horses, and dogs. Two other #2m-specific antibodies reacted only with PBL from chimpanzees. No reaction could be detected with all our reagents in other classes tested (birds, reptiles, amphibians, and Teleostei).     

Stem elongation and floral initiation on in vitro chicory root explants: influence of photoperiod

Chicory root explants (Cichorium intybus L.) were cultured in vitro under different photoperiods. In complete darkness, strong stem elongation, but no flowering induction was observed. We suggest that this stem elongation could be homologous to the pit growth in chicory heads in vivo. Under a photoperiod of 12 h (LI=±40 E m^–2 s^–1), only vegetative growth was observed. Photoperiods of 16 h or more light a day induced the in vitro explants to develop stems bearing flower buds. When the in vitro cultures were kept in the dark for different durations starting from the first day of culture and afterwards transferred to long-day conditions, 4 days dark were sufficient to cause a decrease in flowering induction. We suggest that during the dark culture, a flowering inhibitory process was started.     

Developmental aspects of the innervation of skeletal muscle fibers in the chick embryo

Summary The M. complexus in the chick, commonly called the hatching muscle, undergoes conspicuous growth during the latter stages of embryonic development. Myogenesis of this muscle was compared to that of M. biceps femoris with regard to development of types of muscle fiber and their innervation. In both muscles fibers are of relatively uniform size and show little growth in diameter between 12 days of development and hatching; fibers develop continuously and display a wide range of diameters at all stages.Initial thickenings on the sarcolemma of fibers where axons are closely approximate were first observed at 10 days of development in both muscles. In both muscles fibers are innervated prior to fibers. Terminal axon networks bridge intercellular spaces and contact fibers in different myogenic clusters, fibers that develop on the surface membrane of fibers exhibit focal thickenings of the membrane and some cell projections that are directed toward axon- fiber contacts. These changes occurred only in fibers of M. complexus.At 14 days of embryogenesis, the processes of synaptogenesis and of myelin formation are less advanced in M. biceps femoris than in M. complexus. At this stage a fibers were observed to be innervated in M. complexus, but not yet in M. biceps femoris. Each fiber was observed to be encircled by several preterminal axons.It is concluded that the earlier development of M. complexus is correlated with an equally early development of nerve-muscle interactions.This work was supported in part by a grant from the Muscular Dystrophy Association of America, Inc.Postdoctoral Fellow of the Muscular Dystrophy Association I would like to thank Professor Dr. H. Tamate for his valuable advise. I am also grateful to Dr. L. Doerr, H. Stokes and Judi K. Lund for their advice and skilled technical assistance     

Localization of Acetyl Groups in the Macromolecule of Glucomannan Obtained from Roots of Eremurus zangezuricus

Water-soluble glucomannan from roots of Eremurus zangezuricus Mikheev was studied. The polysaccharide contains D-glucose, D-mannose, and acetyl groups in the molecular ratio of 1 : 2.8 : 0.38. ¹³C NMR studies showed that the polysaccharide under study is a linear, partly acetylated 1,4--D-glucomannan. The acetyl groups are attached to the C2 and C3 of mannopyranose units. The polymer contains, on average, one acetyl group per seven mannose units. The glucomannan of E. zangezuricus has the following parameters: []_D = –37.5°, [] = 3.73 dl/g, and Mw = 151 kDa.     

A model for refractoriness accumulation and secondary range firing in spinal motoneurones

A model is presented in which the potassium conductance (G _K ) changes responsible for the afterhyperpolarization (AHP) in motoneurones are postulated to follow a kinetics coherent with Hodgkin-Huxley membrane model. Such G _K kinetics, which operates as a bistable system switched from one state to the other by the action potential, can be expressed by simple analytical expressions if the spike is approximated to a rectangular pulse. Accumulation of G _K by repetitive activation of the model accurately describes the different features of AHP summation in motoneurones; moreover, this accumulation process enables a model for repetitive firing of motoneurones to display secondary range firing at steady state.     

The foot cell morphology of genus Aspergillus

The paper deals with the morphology, development and nature of foot cell in the genusAspergillus. About 69 species belonging to 14 groups have been studied.A. brunneo-uniseriatus (Singh &Bakshi),A. nidulans (Eidam)Wint andAspergillus sp. (ofA. clavatus group) have been selected for detailed developmental studies as they were found to be representative forms of various types of foot cells met within the genus. The foot cell appeared as an enlarged hyphal cell, which, depending upon position of conidiophore became I, L and T shaped but in species ofA. clavatus andA. wentii group it was branched and rhizoidal type due to the development of side protubrances. Effect of different media, pH, sugar concentration and light on foot cell morphology has also been studied. Different media, pH of basal medium and sugar concentration did not show any marked effect on the development and morphology of foot cell while light showed pronounced effect on species ofA. clavatus group.     

Die Hemmung der Phytochrominduzierten Photomorphogenese („Positive” Photomorphosen) des Senfkeimlings (Sinapis alba L.) Durch Actinomycin D und Puromycin

Zusammenfassung Die positiven Photomorphosen Öffnung des Hypokotylhakens und Entfaltung der Kotyledonen können ganz ähnlich wie die phytochrominduzierte Anthocyansynthese und andere positive Photomorphosen durch Actinomycin D und Puromycin gehemmt werden. Man kann daraus schließen, daß diese beiden photomorphogenetischen Reaktionen des Senfkeimlings ebenfalls durch eine von P₇₃₀ über eine Signalkette ausgelöste Aktivierung von potentiell aktiven Genen veranlaßt werden.

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The inhibition of phytochrome-mediated photomorphogenesis (positive photoresponses) by actinomycin D and puromycin in the mustard seedling (Sinapis alba L.)

Summary The many photochrome-mediated photoresponses of a seedling (Sinapis alba L., white seeded mustard) can be divided into 3 categories: positive, negative, and complex photoresponses. Positive photoresponses are those which are characterized by an initiation or a promotion of biosynthetic or growth processes (Mohr, 1966b). Phytochrome-mediated anthocyanin synthesis is the prototype of a positive photoresponse. It has been shown in previous papers (e.g. Lange and Mohr, 1965; Mohr et al., 1965) that positive photoresponses can be specifically inhibited by actinomycin D and puromycin. It has been concluded that in the case of positive photoresponses P₇₃₀ (the active phytochrome) exerts its function through differential gene activation.—In the present paper it has been demonstrated that phytochrome-mediated positive photoresponses of the mustard seedling like opening of the hypocotylar hook and unfolding of the cotyledons can be inhibited by relatively low doses of actinomycin D and puromycin in very much the same way as anthocyanin synthesis or cotyledon enlargement is inhibited. It has been concluded that in these cases too the action of P₇₃₀ must be attributed to an activation of potentially active genes in the manner postulated on the basis of the data on anthocyanin synthesis.

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Die Arbeit wurde durch Sachbeihilfen der Deutschen Forschungsgemeinschaft und der Stiftung Volkswagenwerk (an Prof. Mohr) ermöglicht.     

Cholinesterases and cell proliferation in “nonstratified” and “stratified” cell aggregates from chicken retina and tectum

Summary Dissociated single cells from chicken retina or tectum kept in rotation-mediated cell culture aggregate, proliferate and establish a certain degree of histotypical cellto-cell relationships (sorting out), but these systems never form highly laminated aggregates (nonstratified R- and T-aggregates). In contrast, a mixture of retinal plus pigment epithelial cells forms highly stratified aggregates (RPE-aggregates, see Vollmer et al. 1984). The present comparative study of stratified and nonstratified aggregates enables us to investigate the process of cell proliferation uncoupled from that of tissue stratification. Here we try to relate these two basic neurogenetic processes with patterns of expression of cholinesterases (AChE, BChE) during formation of both types of aggregates.During early aggregate formation, in both stratified and nonstratified aggregates an increased butyrylcholinesterase activity is observed close to mitotically active cells. Quantitatively both phenomena show their maxima after 2–3 days in culture. In contrast, AChE-expression in all systems increases with incubation time. In nonproliferative areas, in the center of RPE-aggregates, the formation of plexiform layers is characterized initially by weak BChE and then strong AChE-activity. These areas correspond with the inner (IPL) and outer (OPL) plexiform layers of the retina in vivo. Although by sucrose gradient centrifugation we find that the 6S- and the fiber-associated 11S-molecules of AChE are present in all types of aggregates, during the culture period the ratio of 11S/6S-forms increases only in RPE-aggregates, which again indicates the advanced degree of differentiation within these aggregates.It is thus demonstrated that cholinesterases first correlate with neuronal cell proliferation and later with stratification, which indicates functions of both enzymes during both developmental periods.Abbreviations AChE acetylcholinesterase - BChE butyrylcholinesterase - iso-OMPA specific inhibitor of BChE - BW 284C51 specific inhibitor of AChE - IPL inner plexiform layer - OPL outer plexiform layer     

Inhibition of (+)[3H]SKF 10,047 binding to rat brain membranes by FAB fragments from a monoclonal antibody directed against the opioid receptor

Examination of the binding of (+)[³H]SKF 10,047 to rat brain membranes indicated that at a low concentration most of the binding was to the haloperidol-sensitive binding site. Titration curves exhibited a displacement potency order of haloperidol >(+)SKF 10,047 =1,3-diorthotolyl-guanidine(–)SKF 10,047 phencyclidine analogues. The effect of Fab fragments from a monoclonal antibody, OR-689.2.4, directed against the opioid receptor on the binding of(+)[³H]SKF 10,047 to rat brain membranes was examined. The specificity of this antibody for the opioid receptor has been determined by its ability to inhibit the binding of and opioid peptides to rat brain but not the binding of opioid ligands or nonopioid ligands specific for other receptors. The Fab fragments blocked and displaced specifically bound (+)[³H]SKF 10,047 in a titratable manner. Increasing the incubation time of the membranes with the Fab fragments increased the percent inhibition obtained. The Fab fragments acted as noncompetitive inhibitors of (+)[³H]SKF 10,047 binding. A(+)SKF 10,047 binding site in rat brain appears to share a common structural domain with and opioid receptors.     

The effect of in vitro pretreatments on subsequent shoot organogenesis from excised Rubus and Malus leaves

Shoot regeneration from Rubus leaves was obtained on a medium containing MS salts, vitamins and sugars, Staba vitamins, casein hydrolysate (100 mg l^–1) and 10 M thidiazuron. Shoot regeneration from Malus leaves was obtained on N⁶ rice anther medium with 5 M thidiazuron. In vitro pretreatment of source shoots with either colchicine or thidiazuron enhanced the organogenic potential of detached leaves of two Rubus hybrids. The response to colchicine was quadratic and occurred at non-mutagenic concentrations (75–250 M). The response to thidiazuron was exponential between 0 and 5 M. When applied as a pretreatment, the effectiveness of several different cytokinins (benzyladenine, thidiazuron, zeatin) at enhancing Malus and Rubus organogenesis was related to the shoot proliferation activity of the cytokinin and to treatment-induced variation in leaf and petiole size.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - IBA indolebutyric acid - MS Murashige & Skoog basal medium devoid of plant growth regulators - OI organogenesis-initiating subculture - PTI colchicine pretreatment subculture - PTII cytokinin pretreatment subculture - NAA naphthaleneacetic acid - TDZ thidiazuron - zeatin trans-zeatin     

<Emphasis Type="Italic">In vitro</Emphasis> Blastogenesis inhibited by <Emphasis Type="Italic">Erwinia carotovora</Emphasis><Emphasis Type="SmallCaps">L</Emphasis>-Asparaginase

Escherichia coliL-asparaginase, an antileukaemic agent in man¹, inhibits in vitro mitogen or antigen-induced blastogenesis in man^2,3 and in animals (M. Bennett, E. G. Mayhew and T. Han, unpublished data) and suppresses bone-marrow derived antibody precursor cells in the mouse⁴. We now report that another L-asparaginase preparation—from Erwinia carotovora—also possesses antileukaemic activity^5,6 and has a more pronounced immunosuppressive effect on in vitro blastogenesis than the E. coli enzyme.     

Kinetic properties of bovine brain proteinl-isoaspartyl methyltransferase determined using a synthetic isoaspartyl peptide substrate

Proteinl-isoaspartyl methyltransferase, an enzyme enriched in brain, is implicated in the repair of age-damaged proteins containing atypical, isoaspartyl peptide bonds. We have investigated the kinetics of methylation using a synthetic peptide substrate having the structure Trp-Ala-Gly-Gly-isoAsp-Ala-Ser-Gly-Glu. Double-reciprocal plots of initial velocity versus concentration of S-adenosylmethionine (AdoMet) at different fixed concentrations of peptide gave straight lines converging at a positive 1/v value and a negative 1/AdoMet value. The product S-adenosylhomocysteine (AdoHcy) was a competitive inhibitor towards AdoMet and a linear mixed-type inhibitor towards peptide. These results are consistent with the rapid-equilibrium random sequential bi-bi mechanism previously proposed for the enzyme, but they also reveal the formation of the deadend, enzyme-peptide-AdoHcy, complex. The rate constants were:V _max=32–34 nmol/min/mg,K ^peptide=7.6–9.4 M,K ^AdoMet=1.9–2.2 M, =0.43–0.53,K ^AdoHcy=0.08 M, =2.9. The interaction factors and indicate that binding of enzyme to peptide increases its affinity for AdoMet and decreases its affinity for AdoHcy. Methylation was linear with time throughout the transfer of 2 mol of methyl groups/mol of enzyme. This absence of burst kinetics suggests that slow release of products cannot explain the low turnover number.Special issue dedicated to Dr. Paul Greengard     

Cloning of Maytenus emarginata (Willd.) Ding Hou — a tree of the Indian Desert,through tissue culture

Summary An in vitro method for cloning and mass multiplication of Maytenus emarginata, a highly drought resistant tree of the Indian Desert, has been developed. Shoot segments harvested from a plus tree (30-year-old) were cultured to produce multiple shoots (10–15 shoots/explant) on MS medium containing 0.1 mgl^–1 IAA and 2.5mgl^–1 BAP. In vitro produced shoots were cut into segments and cultured on shoot proliferation medium but with only 1.0 mgl^–1 of BAP to further multiply the shoots. Isolated individual shoots were cultured on a filter paper bridge in half strength MS liquid medium containing 25 mgl^–1 of IBA for 72 h in the dark at 28±2⁰ C for induction of root(s). About 70–80 percent of shoots rooted. The treelets developed were hardened and transferred to pots. Around 20,000 plants can be obtained from a single explant within a period of 6 months. The protocol is highly reproducible and efficient.Abbreviations IAA indole-3-acetic acid - IBA indole-3-butyric acid - NAA -naphthalene acetic acid - NOA -naphthoxy acetic acid - BAP 6-benzylaminopurine - Kn 6-furfurylaminopurine - B5 Gamborg et al. (1968) medium - MS Murashige and Skoog (1962) medium     

Expression of the C3-C4 intermediate character in somatic hybrids between Brassica napus and the C3-C4 species Moricandia arvensis

The wild crucifer Moricandia arvensis is a potential source of alien genes for the genetic improvement of related Brassica crops. In particular M. arvensis has a C₃-C₄ intermediate photosynthetic mechanism which results in enhanced recapture of photorespired CO₂ and may increase plant water-use efficiency. In order to transfer this trait into Brassica napus, somatic hybridisations were made between leaf mesophyll protoplasts from cultured M. arvensis shoot tips and hypocotyl protoplasts from three Brassica napus cultivars, Ariana, Cobra and Westar. A total of 23 plants were recovered from fusion experiments and established in the greenhouse. A wide range of chromosome numbers were observed among the regenerated plants, including some apparent mixoploids. Thirteen of the regenerated plants were identified as nuclear hybrids between B. napus and M. arvensis on the basis of isozyme analysis. The phenotypes of these hybrids were typically rather B. napus-like, but much variability was observed, including variation in flower colour, leaf shape and colour, leaf waxiness, fertility and plant vigour. CO₂ compensation point measurements on the regenerated plants demonstrated that 3 of the hybrids express the M. arvensis C₃-C₄ intermediate character at the physiological level. Semi-thin sections through leaf tissues of these 3 plants revealed the presence of a Kranz-like leaf anatomy characteristic of M. arvensis but not found in B. napus. This is the first report of the expression of this potentially important agronomic trait, transferred from Moricandia, in M. arvensis x B. napus hybrids.