1,720,991 research outputs found
Morphogenesis of the giant sperm axoneme in Asphondylia ruebsaameni Kertesz (Diptera, Cecidomyiidae)
No full textThe formation of the sperm giant axoneme of the gall-midge fly Asphondylia ruebsaameni is described
here. The axoneme consists of a great number of microtubular doublets (up to 2500) arranged in a double spiral
wrapping around an axial cluster of mitochondria. Each microtubular doublet is provided with an outer arm only.
In the early spermatid the occurrence of a large system of curved multi-layered filamentous material associated
with membranous cisternae has been observed in the perinuclear region. Such a system extends throughout the
cytoplasm to contact the plasma membrane. The filamentous material appears to act as a nucleating centre for
the assembly of the microtubular doublets, which initially have a submembranous location and later are distributed
in the interior of the cell. After their assembly, microtubular doublets are associated pairwise and are
arranged in a single microtubular row with a zig-zag configuration. This configuration changes during spermiogenesis
as a consequence both of a rotation of the microtubular doublet pairs and a compaction of the axonemal
complex due to the elimination of the excess cytoplasm. As a result of this process, a double parallel spiral of
microtubular doublets is forme
Bacteria associated with the oesophageal bulb of the medfly Ceratitis capitata (Diptera: Tephritidae)
No full textExtracellular Gram negative bacteria were found to be commonly associated to the oesophageal bulb of Ceratitis capitata with Klebsiella oxytoca and Enterobacter agglomerans as the most common species. All the isolates tested in vitro, except one, were sensitive to the antibacterial material present on the medfly laid egg surface
Presence of antibacterial peptides on the laid egg chorion of the medfly Ceratitis capitata
No full textFemale reproductive accessory glands of the medfly Ceratitis capitata produce a secretion with antibacterial activity mainly ascribed to ceratotoxin peptides. To study whether the secretion from the accessory glands of the female protects the eggs and early larva from microbes, we examined whether ceratotoxins and other accessory gland components could be found on the egg surface. This was found to be the case; a water-soluble material with the same protein and antibacterial pattern as that of the accessory gland secretion was recovered from the laid egg surface and was observed as electrondense, clustered droplets over the outer exochorion. Such material showed the same electrophoretic pattern in both mated and virgin females. These findings indicate that the accessory gland secretion is spread, at oviposition, onto the eggs producing an antibacterial coating, irrespective of fertilization. This is the first report of antimicrobial components recovered from a material layered on insect laid eggs
Controllo biologico della mosca mediterranea della frutta, Ceratitis capitata, mediante l'uso di tecniche biomolecolari
No full textIn the present paper we show biochemical and molecular biology studies on the female reproductive accessory gland secretion from Ceratitis capitata wild flies of different origin. The gland secretions from all the populations we analyzed share the same electrophoretic pattern and the antibacterial female-specific peptides ceratotoxins, previously characterized by our research group, are found in all the populations. Southern blot analysis shows that the ceratotoxin genes share the same genomic organization in all the populations. Therefore, we can consider the use of ceratotoxin promoters to control the reproduction of C. capitata natural populations
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Juvenile hormone regulates the expression of the gene encoding ceratotoxin A, an antibacterial peptide from the female reproductive accessory glands of the medfly Ceratitis capitata
No full textCeratotoxin A is an antibacterial peptide produced by the reproductive female accessory glands of the medfly Ceratitis capitata. To investigate whether ceratotoxin A gene expression was affected by juvenile hormone, which has gonadotropic functions in adult insects, newly emerged female medflies were treated with precocene II, an antiallotropin compound capable of inhibiting juvenile hormone biosynthesis. Daily treatment of newly emerged flies with precocene II blocked ceratotoxin A gene expression in a dose-dependent manner. Ceratotoxin A gene expression could be recovered after withdrawl of precocene II treatment. Moreover, the effect of precocene II on ceratotoxin A gene expression could be countered by simultaneous treatment with methoprene, a juvenile hormone analogue. The effects of precocene II and methoprene treatments on the growth of both ovaries and accessory glands was also investigated. Our data suggest that ceratotoxin A gene expression is modulated by juvenile hormone
Sequence of two cDNA clones from the medfly Ceratitis capitata encoding antibacterial peptides of the cecropin family
No full textUsing a back translated oligodeoxyribonucleotide probe, encoding a conserved motif in insect antibacterial peptides, we have isolated two cDNA clones from the medfly, Ceratitis capitata. Sequence determination shows that the cDNAs encode two closely related peptides which are members of the cecropin family
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