Life Sciences

M. Mandrioli Dipartimento di Biologia Animale, Universita' di Modena e Reggio Emilia, Via Campi 213/D, 41100 Modena, Italy; Tel: (+39) 59 2055544; Fax: (+39) 59 2055548; E-mail: mandriol@unimo.it ... Received 3 December 2001. Received in revised form and ...

An emerging central concept in evolutionary biology suggests that symbiosis is a universal characteristic of living organisms that can help in understanding complex traits and phenotypes. During evolution, an integrative circuitry fundamental for survival has been established between commensal gut microbiota and host. On the basis of recent knowledge in worms, flies, and humans, an important role of the gut microbiota in aging and longevity is emerging. The complex bacterial community that populates the gut and that represents an evolutionary adapted ecosystem correlated with nutrition appears to limit the accumulation of pathobionts and infections in all taxa, being able of affecting the efficiency of the host immune system and exerting systemic metabolic effects. There is an urgent need to disentangle the underpinning molecular mechanisms, which could shed light on the basic mechanisms of aging in an ecological perspective. Thus, it appears possible to extend healthy aging and lifespan by targeting the host as a metaorganism by manipulating the complex symbiotic ecosystem of gut microbiota, as well as other possible ecosystems of the body.

Primary cell cultures of immunocytes have been developed from the three psyllid species Cacopsylla melanoneura, Cacopsylla pyri (vectors of 'Candidatus Phytoplasma mali' and 'Candidatus Phytoplasma pyri', respectively) and Cacopsylla crataegi. The medium most suitable of those evaluated was Hert-Hunter 70 (HH70) psyllid medium. In fact, good survival and proliferation of the Cacopsylla immunocytes for over 60 d were observed, with mitosis activities starting at 15-d post culture. Moreover, adhesion and phagocytosis activities were confirmed for all the psyllid cell cultures by functionality tests. Morphological examination of cultured immunocytes revealed the presence of different cell types in all the three psyllid species in accordance to published data about insect immunocytes. The in vitro maintenance of psyllid immunocytes represents a powerful tool for a wide range of applications, especially for psyllid cell biology. In particular, in-depth studies on the biol...

DNA contents, ranging from 4C to more than 500C, were determined by a quantitative microfluorimetric assay in supramedullary neuron nuclei of the pufferfish Diodon holacanthus. The distribution of C values after ethidium bromide staining indicates an inter- and intra-individual variation in DNA contents which do not correspond to duplications of the total genome, suggesting that DNA replication is specific for particular genes (endoreplication). Moreover, the DNA content appears to be correlated with nuclear size. A relationship between the DNA amounts and the presence of AT- and GC-rich sequences has been shown. This work demonstrates, for the first time, DNA endoreplication in a specific neuronal type in vertebrates.

... VALENTINA MONTI1,2†, MAURO MANDRIOLI1†, MARCO RIVI2 and GIAN CARLO MANICARDI2* ... Irradiation of Aphis gossypii (Glover) and Aphis nerii (Boyer de Fonsco-lombe) specimens produced several breaks occurring mainly on autosome 1 and never on the X chromo ...

In recent years aphids, with their well-defined polyphenism, have become favoured as model organisms for the study of epigenetic processes. The availability of the pea aphid (Acyrthosiphon pisum) genome sequence has engendered much research aimed at elucidating the mechanisms by which the phenotypic plasticity of aphids is inherited and controlled. Yet so far this research effort has paid little attention to the cytogenetic processes that play a vital part in the organisation, expression and inheritance of the aphid genome. Aphids have holocentric chromosomes, which have very different properties from the chromosomes with localised centromeres that are found in most other organisms. Here we review the diverse forms of aphid chromosome behaviour that occur during sex determination and male and female meiosis, often in response to environmental changes and mediated by endocrine factors. Remarkable differences occur, even between related species, that could have significant effects on the inheritance of all or parts of the genome. In relation to this, we review the particular features of the distribution of heterochromatin, rDNA genes and other repetitive DNA in aphid chromosomes, and discuss the part that these may play in the epigenetic modification of chromatin structure and function.

The induction of anti-microbial peptides against Gram positive and negative bacteria in the IZD-MB-0503 cell line from the lepidopteran Mamestra brassicae is demonstrated, while no anti-fungal activity is detected. The identification of a defensin-like molecule active against Gram positive bacteria is described for the first time in Lepidoptera. This molecule shows between 43% and 59% homology with group A defensins from other dipteran and hymenopteran species.

In this study, we present cytogenetic data regarding 66 Myzus persicae strains collected in different regions of Italy. Together with the most common 2n = 12 karyotype, the results showed different chromosomal rearrangements: 2n = 12 with A1-3 reciprocal translocation, 2n = 13 with A1-3 reciprocal translocation and A3 fission, 2n = 13 with A3 fission, 2n = 13 with A4 fission, 2n = 14 with X and A3 fissions. A 2n = 12-13 chromosomal mosaicism has also been observed. Chromosomal aberrations (and in particular all strains showing A1-3 reciprocal translocation) are especially frequent in strains collected on tobacco plants, and we suggest that a clastogenic effect of nicotine, further benefited by the holocentric nature of aphid chromosomes, could be at the basis of the observed phenomenon.