Thickness Fluctuations in Veins of Corn and Sunflower detected by a Linear Transducer

A short-stroke linear displacement transducer has been usedto detect changes in thickness of veins of corn and sunflower.After illumination, continual fluctuations in thickness occurred,some 2–5 min and others 15–20 min apart and from0.05% to 2% of the total vein thickness in amplitude. Thesechanges, often erratic and usually not simultaneous at points4.0 cm apart, seem to be related to changes in water potentialin the tissue. The short-term fluctuations were not due to majorstomatal oscillations but could be due to local variations intranspiration, or to fluctuations in photosynthate moving throughthe veins, for they often resembled the patterns of radioactivitydetected after feeding ¹¹CO₂or ¹¹C-sucrose. The magnitude offluctuation increased as the diameter of vein increased, andthus could be useful in monitoring changes of water potentialin leaves.     

Cladispa Baly: revision,biology and reassignment of the genus to the tribe Spilophorini (Coleoptera: Chrysomelidae: Cassidinae)

The genus, Cladispa Baly 1858, is transferred from the tribe Imatidiini (= Cephaloleiini Chapuis, 1875) to Spilophorini Chapuis, 1875 based on the review of type material, newly collected specimens and molecular phylogenetic analysis. The type species, C. quadrimaculata Baly, 1858, is redescribed, and two new species, C. amboroensis sp.n. from Bolivia (Santa Cruz Department) and C. ecuadorica sp.n. from Ecuador (Pastaza Province), are described and figured. The morphology of C. amboroensis sp.n. immature stages is broadly consistent with other Spilophorini. Field observations document that both C. quadrimaculata and C. amboroensis sp.n. are trophic specialists on Orchideaceae. Keys to Cladispa species and Spilophorini genera are provided. Trophic associations of other Cassidinae and Orchideaceae are discussed. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:42A1ECF3‐2030‐4938‐8F3D‐FE7EC36F303A     

Manganese and zinc in the ovipositors and mandibles of hymenopterous insects

X-ray microanalysis of the ovipositor and mandibles of various hymenopterous insects has revealed the presence in many species of up to 10% wt/wt of either zinc or manganese in the cuticle. These metals appear to be involved in cuticular hardening, so helping to reduce abrasive wear. Zinc is found in the ovipositors of most Siricidae, Stephanoidea, and Chalcidoidea. In Ichneumonoidea and Cynipoidea, the metal involved is manganese. Megalyroidea are unique in the Hymenoptera in having both zinc and manganese in their ovipositors, though in different locations. Except for Bethylidae, no metals were detected in the ovipositors or stings of species that penetrate soft substrates or do not make holes at all. The cutting edge of the mandibles of many insects that chew their way through hard substrates during egress from their pupation sites almost invariably contain high concentrations of zinc, and this is present in many that lack metals in their ovipositor. The phylogenetic and ecological implications of metal occurrence are discussed.     

In situMechanical Testing of Fully Hydrated Carrots (Daucus carota) in the Environmental SEM

We demonstrate the use of the Environmental Scanning ElectronMicroscope (ESEM) forin situobservation of mechanical testson carrot (Daucus carota)parenchymal tissue. The ESEM toleratesseveral Torr of water vapour in the specimen chamber, thus allowingfully hydrated specimens to be examined at high resolution,but without preparation. Three tests were performed, involvingslicing, tension and compression. The manner in which stresswas distributed in the tissue, crack propagation and cell walldistortion were all observed in real time.Copyright 1998 Annalsof Botany Company. Environmental scanning electron microscopy, carrot,Daucus carota,mechanical testing.     

Hyperdipsia after Serotonin-depleting Midbrain Lesions

VISUALIZATION of brain monoamines by histochemical fluorescence reveals that almost all forebrain serotonin (5-hydroxy-tryptamine) derives from cell bodies in the dorsal and median raphe nuclei of the midbrain¹. While studying the shock thresholds of rats with lesions of these raphé nuclei, we noticed that home cage water supplies of experimental animals were often more depleted than those of controls (paper presented at Winter Conference on Brain Research, 1971). Since all rats were given similar amounts of fresh food and water daily, this observation implied increased drinking by lesioned animals. This paper summarizes systematic observations confirming that such animals drink more water than controls and additionally suggests that this hyperdipsia is not secondary to involuntary water loss. As far as we know, this is the first report of increased water intake after selective disruption of serotoninergic neural systems in brain.     

Colonisation by Dreissena of Great Lakes coastal ecosystems: how suitable are wetlands?

1.  Invasive zebra ( Dreissena polymorpha ) and quagga mussels ( Dreissena bugensis ) have become widespread throughout the Great Lakes basin. However, some types of Great Lakes coastal wetlands may be unsuitable for Dreissena invasion.
2.  To test this observation, artificial substrata were placed in wetlands (with emergent vegetation) and in adjacent open water (without emergent vegetation) habitats in two types of Great Lakes coastal ecosystems: drowned river mouth (DRM) and coastal fringing systems. Wetlands in DRM systems generally have deep organic sediment and limited water movement, whereas coastal fringing wetlands generally have low to moderate amounts of organic sediment and intense wind and wave action.
3.  We did not find a significant difference in Dreissena colonisation between wetlands and adjacent open water habitat in fringing systems. However, Dreissena colonisation was significantly lower in DRM wetlands than in the adjacent open water. We also found significantly lower survival in DRM wetlands than adjacent open water habitats, whereas survival did not differ significantly in coastal fringing wetlands and the adjacent open water.
4.  Our results suggest that vulnerability to Dreissena invasion varied among wetland types with DRM wetlands being less suitable than fringing wetlands. We suggest that colonisation and survival of Dreissena is lower in wetlands with deep organic sediment and less turbulent water.     

Modification of Tobacco Leaf Glycolate Oxidase Activity by Chlorogenic Acid and Other Polyphenols

Glycolate oxidase extracted from tobacco leaves (Nicotiana tabacum L. cv. NC-95) and assayed by the 2,6-dichlorophe-nolindophenol reduction method was stimulated by chlorogenic acid and other o-diphenols but not by p-diphenols such as hydroquinone. Chlorogenic acid also protected the enzyme against certain enzyme antagonists. A novel assay utilizing horseradish peroxidase with the chromogen o-dianisidine was developed for detecting glycolate oxidase in conjunction with disc electrophoresis. Dissociation of glycolate oxidase into an active monomer during ammonium sulfate fractiona-tion was confirmed electrophoretically. After electrophoresis, flavin mononucleotide was required for monomer activity whereas chlorogenic acid was inhibitory to enzyme band development.     

Simulation and Prediction of Plant Phenology for Five Crops Based on PhotoperiodxTemperature Interaction

This paper presents a plant phenological model based on genotypextemperaturexphotoperiodinteraction (GPTmodel). In the model, rate of development towardsa specified stage (e.g. flowering) for a given genotype is composedof three components: the genotype's maximum rate of development;any delay due to a non-optimal temperature; and any delay dueto a photoperiod response. It is assumed that development tothe specified stage is an autonomous process established bymost, if not all, genes other than the vernalization genes andthe photoperiod genes; and that this autonomous process is delayedby any activity of the photoperiod genes. Since all physiologicalprocesses are modulated by temperature, any photoperiod responseis inevitably a photoperiodxtemperature interaction. This interactionis simulated by assuming that the photoperiod gene activityoccurs only beyond a critical photoperiod (P_c) and is enlargedby temperature above a base temperature (T_bp) that allows thephotoperiod gene activity. The model is written asR=1/D_b-S_t(T-T_opt)²-S_p(T-T_bp)|P-P_c|, whereRis the expected rate of development to the specifiedstage under any combination of temperature (T) and photoperiod(P). The other model parameters are:S_p, the sensitivity to adelaying photoperiod;T_opt, the optimum temperature for developmentin the absence of the photoperiod response;S_t, the sensitivityto a non-optimum temperature; andD_b, the basic duration to thespecified stage (or intrinsic earliness), the inverse of whichis the maximum rate of development.D_bis observable only ifT=T_optandsimultaneouslyP