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Histamine-like immunoreactivity in the visual system and brain of an orthopteran and a hymenopteran insect (1996)

Bornhauser, Beat C. ; Meyer, Eric P.

Springer

Cell & tissue research 287 (1996), S. 211-221

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ISSN: 1432-0878

Keywords: Key words: Immunocytochemistry ; Photoreceptor cells ; Neurotransmitters ; Insect brain ; Fluorescent dyes ; Gryllus campestris (Insecta) ; Apis mellifera (Insecta)

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract. The distribution of histamine-like immunoreactivity has been analyzed in the visual system and brain of the cricket Gryllus campestris and of the bee Apis mellifera by using an antiserum against histamine. Specific immunolabeling of the photoreceptors has been found in the compound eyes and ocelli of both examined species. Intense immunostaining can be also detected in the midbrain of these species. The axons of immunoreactive cells innervate almost every area in the protocerebrum. Most of the reactive neurons are typically wide-field neurons with bilateral ramifications that form dense arborizations. Numerous small buttons on the arborizations probably represent pre- and postsynaptic sites. The histamine-like immunoreactive neurons are apparently connected to many postsynaptic neurons. In both bees and crickets, some regions of the nervous system such as the first two optic neuropils and the central body show the same labeling pattern, whereas the mushroom bodies exhibit no immunoreactivity. Nevertheless, several differences in the staining pattern can be seen: the glomeruli of the antennal lobe are invaded by histamine-like immunoreactive fibers in the bee but not in the cricket. Furthermore, an interneuron connects the second and third optic neuropil in the cricket, whereas no histamine-like immunoreactive interneuron is found in the second optic neuropil in the bee. In accord with the work of other authors on the distribution histamine in the insect nervous system, we suggest that histamine is not only a transmitter within the visual system, but also a transmitter or co-transmitter in the insect midbrain.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004410050747

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The differential expression of the G surface antigen alleles in Paramecium primaurelia heterozygous cells correlates to macronuclear DNA rearrangement (1992)

Keller, Anne-Marie ; Mouël, Anne Le ; Caron, François ; [et al.]

Chichester [u.a.] : Wiley-Blackwell

Developmental Genetics 13 (1992), S. 306-317

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ISSN: 0192-253X

Keywords: Surface antigen ; Paramecium primaurelia ; macronuclear DNA ; DNA rearrangement ; Life and Medical Sciences ; Genetics

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology

Notes: The Paramecium primaurelia cell surface is covered with a high molecular weight protein called the surface antigen. Several genes encode alternative surface antigens, but only one is expressed at a time. In addition, each of these genes shows a high degree of allelic polymorphism. Paramecium primaurelia strains 156 and 168 have different alleles of the G antigen gene whose respective antigens can be distinguished in vivo using specific antibodies. An interallelic exclusion phenomenon has been previously described: 94% of the 156/168 heterozygotes express only the 156 allele of the G gene; 6% express both the 156 and the 168 alleles. The phenotype of the heterozygotes is determined at the time of macronuclear differentiation. We have investigated the molecular basis for the different heterozygous phenotypes. Both mRNAs are always produced, and the 156 mRNA is always more abundant than the 168 mRNA. The relative amounts of these messages, however, vary greatly between different heterozygotes and parallel their phenotype. Pushing the analysis further, we show that the copy number of each allele in the macronucleus correlates with the relative amounts of the mRNAs. However, allelic dosage alone is not sufficient to explain the variations of the mRNA ratio. The G antigen gene is located near a telomere in the macronucleus. We show that the distance between the 156G gene and the telomere is different in homozygotes and heterozygotes. It also varies among heterozygotes and is correlated with the mRNA ratio. Thus, we have identified two different parameters, both linked to the genome rearrangements occurring during macronuclear differentiation, that correlate with the relative expression of the two alleles. Two hypotheses concerning the influence of the telomere position on the expression of the gene are discussed. © 1992 Wiley-Liss, Inc.

Additional Material: 7 Ill.