Papers by Alejandro Rabossi
Journal of Insect Physiology, 2016
The remodeling of membrane composition by changes in phospholipid head groups and fatty acids (FA... more The remodeling of membrane composition by changes in phospholipid head groups and fatty acids (FA) degree of unsaturation has been associated with the maintenance of membrane homeostasis under stress conditions. Overall lipid levels and the composition of cuticle lipids also influence insect stress resistance and tissue protection. In a previous study, we demonstrated differences in survival, behavior and Cu/Zn superoxide dismutase gene expression between subgroups of Ceratitis capitata flies that had a reversible recovery from chill-coma and those that developed chilling-injury. Here, we analyzed lipid profiles from comparable subgroups of 15 and 30-day-old flies separated according to their recovery time after a chill-coma treatment. Neutral and polar lipid classes of chill-coma subgroups were separated by thin layer chromatography and quantified by densitometry. FA composition of polar lipids of chill-coma subgroups and non-stressed flies was evaluated using gas chromatography coupled to mass spectrometry. Higher amounts of neutral lipids such as triglycerides, diacylglycerol, wax esters, sterol esters and free esters were found in male flies that recovered faster from chill-coma compared to slower flies. A multivariate analysis revealed changes in patterns of storage and cuticle lipids among subgroups both in males and females. FA unsaturation increased after cold exposure, and was higher in thorax of slower subgroups compared to faster subgroups. The changes in neutral lipid patterns and FA composition depended on recovery time, sex, age and body-part, and were not specifically associated with the development of chilling-injury. An analysis of phospholipid classes showed that the phosphatidylcholine to lysophosphatidylcholine ratio (PC/LPC) was significantly higher, or showed a tendency, in subgroups that may have developed chilling-injury compared to those with a reversible recovery from coma.
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Quimica Viva, Dec 1, 2011
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Gross morphological changes in Ceratitis capitata (Wied.) during metamorphosis within the pupariu... more Gross morphological changes in Ceratitis capitata (Wied.) during metamorphosis within the puparium are described and temporally correlated with the appearance of main differentiation markers. A table that allows determination of physiological age of pupal and ...
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Archives of Biochemistry and Biophysics
There are no reports focusing on glycogen synthesis in Drosophila or other insects that take into... more There are no reports focusing on glycogen synthesis in Drosophila or other insects that take into account the recent advances made in yeast, nematodes, and vertebrates on this subject. The biosynthesis of glycogen in vertebrates and yeast involves an initiation phase requiring autocatalytic intramolecular glucosylation of the core dimeric protein acting as a glycogen initiator synthase, followed by a polymerization phase catalyzed by glycogen synthase (Cao et al., 1995; Cheng et al., 1995). The latter is associated to the initiator and gives rise to unbranched amylose chains. Glycogen formation is completed by the so-called branching enzyme, that ramifies the amylose glucan (Tolmasky and Krisman, 1987; Tolmasky et al., 1998) to form mature glycogen molecules. No insect homologue of mammalian or yeast glycogenins has been biochemically characterized to date. Moreover, there are no known mutant alleles of glycogen in Drosophila or other insects. As soon as the complete Drosophila geno...
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Australian Journal of Entomology
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Comparative Cytogenetics, 2015
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Photochemistry and Photobiology, 2010
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Journal of Economic Entomology, 2003
A laboratory bioassay was developed to determine both the chemical toxicity and the phototoxicity... more A laboratory bioassay was developed to determine both the chemical toxicity and the phototoxicity of the xanthene dye, phloxine B (D&C Red No 28), to the immature stages of the Mediterranean fruit fly, Certitis capitata (Wiedemann). An additional goal was to find out which main tissues are affected first. A low, but significant, level of toxicity was observed when the insects were maintained in the dark: at the point of adult ecdysis, the LC50 was 11.03 mM. As expected, after 8-h exposure of late larva III to light, a high level of mortality was produced (LC50 at ecdysis: 0.45 mM) as a dose-dependent function of dye concentration. At sublethal concentrations of the dye, the surviving insects showed a number of physiological abnormalities. Phloxine B appeared to mainly affect the larval longitudinal muscles as well as the abdominal muscles of ecdysing adults, giving rise to abnormal puparia and failed adult ecdysis, respectively. Moreover, a significant phloxine B-dependent delay in the jumping of surviving larvae for dispersal was documented. This could be attributed to a delay in attaining a threshold weight for jumping and/or to abnormalities in neuromuscular coordination, thus reinforcing the idea of pleiotropic effects of the dye.
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Experimental Gerontology, 2012
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Entomologia Experimentalis et Applicata, 2000
The induction of several biochemical indicators of larval tissue histolysis in the Medfly, Cerati... more The induction of several biochemical indicators of larval tissue histolysis in the Medfly, Ceratitis capitata (Diptera: Tephritidae)(Wiedemann) was studied. Using synchronized third instar larvae, we have determined the time of occurence of gut evacuation (12 h before ...
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Entomologia Experimentalis et Applicata, 1991
... A. Rabossi, GL Boccaccio, P. Wappner & LA Quesada-Allu6 Instituto de Investigaciones Bioq... more ... A. Rabossi, GL Boccaccio, P. Wappner & LA Quesada-Allu6 Instituto de Investigaciones Bioquimicas ... Our results show that the incorporation of radioactive BALA into the puparium cuticle ... ex-tends up to head eversion (See Ashburner, 1989 and Fraenkel & Bhaskaran, 1973, for ...
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The Canadian Entomologist, 1992
Gross morphological changes in Ceratitis capitata (Wied.) during metamorphosis within the pupariu... more Gross morphological changes in Ceratitis capitata (Wied.) during metamorphosis within the puparium are described and temporally correlated with the appearance of main differentiation markers. A table that allows determination of physiological age of pupal and ...
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Australian Journal of Entomology, 2009
Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Facultad de Ciencias Químic... more Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba & Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Universitaria (5000), Córdoba, Argentina.
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Archives of Insect Biochemistry and Physiology, 2004
During larva to adult transition, the larval fat body of the Medfly (Ceratitis capitata) progress... more During larva to adult transition, the larval fat body of the Medfly (Ceratitis capitata) progressively disintegrates to be replaced by the adult one, after imago ecdysis. Here we show that a temporal correlation exists among the microscopy images of fat body progressive disintegration, the activation of fat body lysosomes (as judged by acid phosphatase activity), and the activity of a novel fat body aspartyl proteinase. The enzyme was purified and partially characterized. This proteinase exhibited a wide range of acid isoforms with isoelectric points from 5.6 to 7.3, an optimum pH of 3.0 for hemoglobin digestion, and was completely inhibited by pepstatin A. The apparent molecular weight was estimated (42 +/- 1 kDa) and the protein was characterized as N-glycosylated, judging from affinity to Concanavalin A. From the biochemical characteristics, the enzyme that we called "Early Metamorphosis Aspartyl Proteinase" (EMAP) appears to be similar to mammalian Cathepsin D. However, the N-terminal sequence of EMAP showed no similarity with any known animal Cathepsins and exhibited an important instability to neutral and alkaline pH. This feature seems to be a peculiar characteristic of insect aspartyl proteinases. The temporal activity profile of EMAP during metamorphosis correlated well with the microscopy images of fat body cell autolytic death. Our data support the notion that EMAP is a metamorphosis-specific lysosomal proteinase, mostly expressed during larval fat body histolysis.
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Archives of Insect Biochemistry and Physiology, 2008
In holometabolous insects, there is a complete body remodeling from larva to adult. We determined... more In holometabolous insects, there is a complete body remodeling from larva to adult. We determined in Ceratitis capitata that the transition from pre-pupa to pupa, 40 to 48 h after puparium formation (h APF), is a key moment of metamorphosis; when salivary glands, intestine, fat body, and muscles are in different stages of cell death. At 44-46 h APF, muscles from segments 1-3 (thoracic region) appeared fully disintegrated, whereas posterior muscles just started death processes. To understand some of the biochemical events eventually involved in histolytic processes during early metamorphosis, two cysteine peptidases coined "Metamorphosis Associated Cysteine Peptidase" (MACP-I and MACP-II) were purified to homogeneity from 40-46-h APF insects. Both enzymes were inhibited by Ep-475, a specific inhibitor of papain-like cysteine-peptidases. MACP-I is a single chain protein with an apparent molecular mass of 80 kDa and includes several isoforms with pI values of pH 6.25-6.35, 6.7, and 7.2. The enzyme has an optimum pH of 5.0 and its pH stability ranges from pH 4.0 to 6.0. The molecular weight and N-terminal sequence suggest that MACP-I might be a novel enzyme. MACP-II is an acidic single chain protein with a pI of pH 5.85 and an apparent molecular mass of 30 kDa. The enzyme is labile with a maximum stability in the pH range of 4.0 to 6.0 and an optimum pH among 5.0 to 6.0. MAPCP-II characteristics suggest it is a cathepsin B-like enzyme.
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Archives of Biochemistry and Biophysics, 2001
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Annals of the Entomological Society of America, 2003
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Journal of Insect Science, 2011
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Papers by Alejandro Rabossi