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  • 2000-2004  (2)
  • 1980-1984  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 64 (2004), S. 0 
    ISSN: 1095-8649
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Euspermatozoa and paraspermatozoa of a copulatory (internal insemination with external sperm transfer) cottoid fish Blepsias cirrhosus were observed ultrastructurally. Euspermatozoa of B. cirrhosus consisted of an acrosome-less, thin, disk-like sperm head (1·6-2·0 μm in length and 1·3-1·6 μm in width), a long middle piece, and a long flagellum (c. 30 μm). Aberrant spermatids, which were rich in cytoplasm and possessed two nuclei, occurred in testicular lobules. They were also observed in semen and were round (5·0-5·3 μm in diameter) and biflagellate, suggesting that they are released along with euspermatozoa at ejaculation. The nuclei of aberrant spermatids developed into masses of highly electron-dense globules. Judging from their form, nuclear condition, and connection with normal spermatids by intercellular bridges during spermiogenesis, aberrant spermatids of B. cirrhosus are considered hyperpyrenic paraspermatozoa formed by incomplete cytokinesis at the second meiotic division.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1573-6903
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Injection of pregnant rats with cytosine arabinoside (ara-C) (280 mg/kg) on day 15 of gestation caused a significant rise (about two times the control value) in monoamine concentrations (norepinephrine, dopamine, and serotonin) accompanied by a decrease (about 60% of the control) in the brain weight and DNA content in the cerebrum of the offspring at 60 days of age. When neonatal rats were injected with ara-C (30 mg/kg/day) for four consecutive days from the fourth to seventh days after birth, a decrease of DNA content per cerebellum and an elevation of monoamine concentrations in the cerebellum were found. However, the total content of each monoamine per cerebrum or cerebellum showed no difference from the control. These results suggest that monoaminergic neurons may remain intact, with normal monoaminergic synapses compressed into a small brain volume. The neonatal administration of ara-C caused an elevation of 2′, 3′-cyclic nucleotide 3′-phosphodiesterase (CNPase) (EC 3.1.4.37) activity and myelin protein content in the cerebellum, suggesting a relative increase in myelin concentration as a result of hypoplasia of granule cells.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 300 (2000), S. 459-464 
    ISSN: 1432-0878
    Schlagwort(e): Brain Glia Growth factor In situ hybridization Parasitization Subesophageal ganglion Pseudaletia separata (Insecta) Cotesia kariyai (Insecta)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Parasitization of the armyworm Pseudaletia separata by the endoparasitic wasp Cotesia kariyai inhibits larval growth and delays pupation, conditions necessary for proper maturation of the parasite larvae. Parasitization is correlated with an elevated level of a 25-amino-acid hormone-like peptide, growth-blocking peptide (GBP, ENFSGGCVAGYMRTPDGRCKPTFYQ). Injection of synthetic GBP into nonparasitized larvae dose dependently mimics the effects of parasitization by delaying the larval development. Here we studied the relationship between parasitization and both the production and distribution of GBP in central nervous tissues. We found that parasitization is correlated with an elevated expression of GBP mRNA, and increased concentrations of both proGBP and GBP in the host insect brain and subesophageal ganglion. The increase in proGBP precedes that of the mature GBP by about 12 h. In situ hybridization analysis using sections of parasitized and nonparasitized larval brains showed strong expression of GBP mRNA in perineural cells and/or class I neuroglia in the rind of both larval brains. The expression in parasitized larval brain-subesophageal ganglion is approximately two- to threefold higher than that in nonparasitized larvae. The presence of GBP in insect neural tissue, and its role in inhibiting growth, suggest an involvement in the regulation of neurosecretory cells.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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