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  • 1
    Electronic Resource
    Electronic Resource
    Role of juvenile hormone biosynthesis in dominance status and reproduction of the bumblebee, Bombus terrestris (1993)
    Springer
    Behavioral ecology and sociobiology 33 (1993), S. 335-338 
    Details
    ISSN: 1432-0762
    Keywords: Social insects ; Bumblebee ; Juvenile hormone ; Reproduction ; Dominance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Bombus terrestris females, dominant status is correlated with high levels of juvenile hormone (JH) biosynthesis and rapid oöcyte maturation. Queenright workers, which are inhibited by the dominant queen, complete the cycle of oöcyte maturation while exhibiting a continuous low rate of JH production, but their egglaying is inhibited. Measurements in foundress queens suggest that the low JH titer during oögenesis is probably not responsible for the inhibition of egg-laying. Queenless workers, kept individually, are not activated either for JH production or oöcyte maturation. In groups of three queenless workers, a dominance order becomes established and high rates of JH synthesis are observed in the dominant egg-laying workers, with low rates in subordinated workers. In groups of founder queens, also, a dominance order becomes established and results in a reduced rate of JH production in subordinated females.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00172932
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  • 2
    Electronic Resource
    Electronic Resource
    Immunological evidence for an allatostatin-like neuropeptide in the central nervous system of Schistocerca gregaria, Locusta migratoria and Neobellieria bullata (1995)
    Springer
    Cell & tissue research 279 (1995), S. 601-611 
    Details
    ISSN: 1432-0878
    Keywords: Allatostatin ; Juvenile hormone ; Insect brain ; Neuropeptide ; Corpus allatum ; Corpus cardiacum ; Neurosecretory cells ; Schistocerca gregaria ; Locusta migratoria ; Neobellieria bullata (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Methanolic brain extracts of Locusta migratoria inhibit in vitro juvenile hormone biosynthesis in both the locust L. migratoria and the cockroach Diploptera punctata. A polyclonal antibody against allatostatin-5 (AST-5) (dipstatin-2) of this cockroach was used to immunolocalize allatostatin-5-like peptides in the central nervous system of the locusts Schistocerca gregaria and L. migratoria and of the fleshfly Neobellieria bullata. In both locust species, immunoreactivity was found in many cells and axons of the brain-retrocerebral complex, the thoracic and the abdominal ganglia. Strongly immunoreactive cells were stained in the pars lateralis of the brain with axons (NCC II and NCA I) extending to and arborizing in the corpus cardiacum and the corpora allata. Although many neurosecretory cells of the pars intercerebralis project into the corpus cardiacum, only 12 of them were immunoreactive and the nervi corporis cardiaci I (NCC I) and fibers in the nervi corporis allati II (NCA II) connecting the corpora allata to the suboesophageal ganglion remained unstained. S. gregaria and L. migratoria seem to have an allatostatin-like neuropeptide present in axons of the NCC II and the NCA I leading to the corpus cardiacum and the corpora allata. All these data suggest that in locusts allatostatin-like neuropeptides might be involved in controlling the production of juvenile hormone by the corpora allata and, perhaps, some aspects of the functioning of the corpus cardiacum as well. However, when tested in a L. migratoria in-vitro juvenile hormone-biosynthesis assay, allatostatin-5 did not yield an inhibitory or stimulatory effect. There is abundant AST-5 immunoreactivity in cell bodies of the fleshfly N. bullata, but none in the CA-CC complexes. Apparently, factors that are immunologically related to AST-5 do occur in locusts and fleshflies but, the active protion of the peptide required to inhibit JH biosynthesis in locusts is probably different from that of AST-5.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318172
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  • 3
    Electronic Resource
    Electronic Resource
    Immunological evidence for an allatostatin-like neuropeptide in the central nervous system of Schistocerca gregaria, Locusta migratoria and Neobellieria bullata (1995)
    Springer
    Cell & tissue research 279 (1995), S. 601-611 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Allatostatin ; Juvenile hormone ; Insect brain ; Neuropeptide ; Corpus allatum ; Corpus cardiacum ; Neurosecretory cells ; Schistocerca gregaria ; Locusta migratoria ; Neobellieria bullata (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Methanolic brain extracts of Locusta migratoria inhibit in vitro juvenile hormone biosynthesis in both the locust L. migratoria and the cockroach Diplo-ptera punctata. A polyclonal antibody against allatostatin-5 (AST-5) (dipstatin-2) of this cockroach was used to immunolocalize allatostatin-5-like peptides in the central nervous system of the locusts Schistocerca gregaria and L. migratoria and of the fleshfly Neobellieria bullata. In both locust species, immunoreactivity was found in many cells and axons of the brain-retrocerebral complex, the thoracic and the abdominal ganglia. Strongly immunoreactive cells were stained in the pars lateralis of the brain with axons (NCC II and NCA I) extending to and arborizing in the corpus cardiacum and the corpora allata. Although many neurosecretory cells of the pars intercerebralis project into the corpus cardiacum, only 12 of them were immunoreactive and the nervi corporis cardiaci I (NCC I) and fibers in the nervi corporis allati II (NCA II) connecting the corpora allata to the suboesophageal ganglion remained unstained. S. gregaria and L. migratoria seem to have an allatostatin-like neuropeptide present in axons of the NCC II and the NCA I leading to the corpus cardiacum and the corpora allata. All these data suggest that in locusts allatostatin-like neuropeptides might be involved in controlling the production of juvenile hormone by the corpora allata and, perhaps, some aspects of the functioning of the corpus cardiacum as well. However, when tested in a L. migratoria in-vitro juvenile hormone-biosynthesis assay, allatostatin-5 did not yield an inhibitory or stimulatory effect. There is abundant AST-5 immunoreactivity in cell bodies of the fleshfly N. bullata, but none in the CA-CC complexes. Apparently, factors that are immunologically related to AST-5 do occur in locusts and fleshflies but, the active portion of the peptide required to inhibit JH biosynthesis in locusts is probably different from that of AST-5.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050319
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  • 4
    Electronic Resource
    Electronic Resource
    Quenching of a room temperature fluorescence band at 693 nm during photoactivation of the water-splitting system of Photosystem II in flashed barley leaves (1992)
    Springer
    Photosynthesis research 31 (1992), S. 41-47 
    Details
    ISSN: 1573-5079
    Keywords: Photosystem II ; photoactivation ; in vivo chlorophyll fluorescence ; water-splitting system ; protochlorophyllide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The modifications of the room temperature fluorescence spectrum during the photoactivation of the water-splitting system by continuous illumination were investigated in flashed barley leaves. A blue shift of the chlorophyll fluorescence band was detected during the first 2 min of illumination. During this shift, a decrease of the fluorescence intensity around 693 nm could be demonstrated in difference spectra and in second derivative spectra. This decrease is interpreted as a quenching of PS II fluorescence during the photoactivation. A relative fluorescence increase around 672 nm also occurred during the same period and is thought to reflect rapid light-induced chlorophyll formation. The flashed leaves contained small amounts of photoactive photochlorophyllide which could be removed by a short flash of intense white light given before continuous illumination. The fact that such flash had only weak effect on the 693 nm fluorescence decrease, whereas it strongly reduced the amplitude of the 672 nm fluorescence increase, favours the above interpretations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00049535
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  • 5
    Electronic Resource
    Electronic Resource
    Localization of NADPH-protochlorophyllide reductase in plastids of barley at different greening stages (2000)
    Springer
    Photosynthesis research 64 (2000), S. 63-76 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll synthesis ; chloroplast ; envelope membrane ; greening ; NADPH-protochlorophyllide oxidoreductase ; protochlorophyllide ; thylakoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The localization of protochorophyllide (Pchlide) and of NADPH-protochlorophyllide oxidoreductase (POR, EC 1.6.99.1) within (etio)chloroplasts has been investigated at selected stages of greening of barley seedlings. Pchlide pigment and POR protein contents were evaluated in different plastid membrane fractions by fluorescence spectroscopy and immunoblot analysis using a monospecific polyclonal antibody raised against the purified enzyme. Fluorescence analysis showed the presence of Pchlide in both the envelope and thylakoid membranes. During greening, the Pchlide content, expressed on a total protein basis, decreased in thylakoid membranes, whereas it increased in the envelope membranes. POR proteins were detected mainly in thylakoid membranes at early greening stages. In contrast, the weak amount of POR proteins was associated more specifically with envelope membranes of mature chloroplasts. Whatever the greening stage, thylakoid-bound Pchlide and POR proteins were more abundant in the thylakoid regions which remained unsolubilized after mild Triton treatment used as standard procedure to prepare PS II particles. This suggests the preferential association of Pchlide and POR to the appressed regions of thylakoids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026576319029
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  • 6
    Electronic Resource
    Electronic Resource
    Protochlorophyllide-NADP+ and protochlorophyllide- NADPH complexes and their regeneration after flash illumination in leaves and etioplast membranes of dark-grown wheat (1999)
    Springer
    Photosynthesis research 59 (1999), S. 53-61 
    Details
    ISSN: 1573-5079
    Keywords: fluorescence ; NADPH:protochlorophyllide oxidoreductase ; phototransformation ; POR ; protochlorophyllide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fast (1 min) regeneration process of the photoactive Pchlide forms after a light flash was studied in etiolated wheat leaves, and this process was simulated in vitro by incubating etioplast inner membranes of wheat with excess NADPH or NADP+. The 77 K fluorescence spectra were recorded after flash illumination, dark incubation and a subsequent flash illumination of the samples. A non-photoactive Pchlide form with an emission maximum at 650 nm was transiently detected in leaves during regeneration of a photoactive Pchlide form with an emission maximum at 654 nm. Gaussian deconvolution of fluorescence spectra of isolated membranes showed that this 650 nm form appeared in conditions of excess NADP+, as suggested in previous studies. Additionally a Pchlide form emitting at 638.5 nm was detected in the same conditions. The analysis of the spectra of leaves at different times after a flash indicated that these two non-photoactive forms are involved as intermediates in the regeneration of photoactive Pchlide. This regeneration is in correlation with the production of the Chlide form emitting at 676 nm. The results demonstrate that, in vivo, part of the NADPH:protochlorophyllide oxidoreductase is reloading with nonphotoactive Pchlide on a fast time-scale and that the 676 nm Chlide form is the released product of the phototransformation in this process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006157610954
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  • 7
    Electronic Resource
    Electronic Resource
    Formation of long-wavelength chlorophyllide (Chlide695) is required for the assembly of Photosystem II in etiolated barley leaves (1997)
    Springer
    Photosynthesis research 51 (1997), S. 107-118 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyllide ; etioplasts ; fluorescencespectroscopy ; Photosystem II assembly ; protochlorophyllide ; variable fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlorophyll(ide) spectroscopic properties and Photosystem II assembly, monitored by 77 K variable fluorescence, were studied in etiolated barley leaves as a function of the extent of protochlorophyllide photoreduction by a single millisecond light flash of different intensities. Variable fluorescence, measured 2 hours after the flash, was only detected when the extent of phototransformation was higher than a threshold value of 0.4. Its development paralleled the formation of a chlorophyll emission component at 685 nm, which itself derived from long-wavelength chlorophyllide with an emission maximum at 695 nm. At low flash intensities, short-wavelength chlorophyllide forms preferentially accumulated and no Photosystem II fluorescence was detected after 2 hours. Chlorophyllide esterification was independent of the extent of phototransformation. These results suggested that the formation of long-wavelength chlorophyllide was essential for further assembly of Photosystem II. This interpretation was strengthened by the observed inhibition of both long-wavelength chlorophyllide formation and of variable fluorescence development in leaves treated with δ-aminolevulinic acid or in untreated leaves subjected to repeated flashes of low intensity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005767526448
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