Time filter

Source Type

Dallai R.,University of Siena | Paoli F.,Centro Of Ricerca Per Lagrobiologia E La Pedologia Crea Abp | Mercati D.,University of Siena | Lupetti P.,University of Siena
Tissue and Cell | Year: 2016

The ancestral eukaryotes presumably had an MTOC (microtubule organizing center) which late gave origin to the centriole and the flagellar axoneme.The centrosome of insect early spermatids is in general composed of two components: a single centriole and a cloud of electron-dense pericentriolar material (PCM). During spermiogenesis, the centriole changes its structure and gives rise to a flagellar axoneme, while the proteins of PCM, gamma tubulin in particular, are involved in the production of microtubules for the elongation and shaping of spermatid components. At the end of spermiogenesis, in many insects, additional material is deposited beneath the nucleus to form the centriole adjunct (ca). This material can also extend along the flagellum in two accessory bodies (ab) flanking the axoneme.Among Homoptera Sternorrhyncha, a progressive modification of their sperm flagella until complete disappearance has been verified. In the Archaeococcidae Matsucoccus feytaudi, however, a motile sperm flagellum-like structure is formed by an MTOC activity. This finding gives support to the hypothesis that an evolutionary reversal has occurred in the group and that the cell, when a non-functional centriole is present, activates an ancestral structure, an MTOC, to form a polarized motile bundle of microtubules restoring sperm motility.The presence and extension of the centriole adjunct in the different insect orders is also enlisted. © 2016 Elsevier Ltd. Source

Chiellini C.,Centro Of Ricerca Per Lagrobiologia E La Pedologia Crea Abp | Mocali S.,Centro Of Ricerca Per Lagrobiologia E La Pedologia Crea Abp | Fani R.,University of Florence | Ferro I.,Istituto De Angeli Pharma Division Localita Prulli | Pinzani A.,Istituto De Angeli Pharma Division Localita Prulli
Journal of Microbiological Methods | Year: 2016

Commercially available lyophilized microbial standards are expensive and subject to reduction in cell viability due to freeze-drying stress. Here we introduce an inexpensive and straightforward method for in-house microbial standard preparation and cryoconservation that preserves constant cell titre and cell viability over 14 months. © 2016. Source

Paoli F.,Centro Of Ricerca Per Lagrobiologia E La Pedologia Crea Abp | Roversi P.F.,Centro Of Ricerca Per Lagrobiologia E La Pedologia Crea Abp | Mercati D.,University of Siena | Marziali L.,Centro Of Ricerca Per Lagrobiologia E La Pedologia Crea Abp | And 2 more authors.
Zoologischer Anzeiger | Year: 2015

The ultrastructure of spermiogenesis in four species of Coccoidea, namely Quadraspidiotus perniciosus and Pseudaulacaspis pentagona (Diaspididae), as well as Planococcus citri and Planococcus ficus (Pseudococcidae), is described. Similarly to other coccids, during spermiogenesis sperm nuclei elongate towards the plasma membrane, forming a conical papilla. The microtubule bundles surrounding the nucleus subsequently elongate and a mature sperm is formed. At the end of spermiogenesis, the motile sperm of all the species consists of a cylindrical axial nucleus surrounded by a spiral (Q. perniciosus) or by concentric rings of microtubules (P. pentagona, P. citri and P. ficus) forming a peculiar flagellum. Other features common to all these species are the lack of centrioles, acrosome and mitochondria in the spermatid and mature sperm. Differences arise in the number of spermatid cells per cyst (32 in Q. perniciosus and 16 in the other three species) and in the number and arrangement of microtubules forming the flagellum. Details on the origin of the flagellum and on the formation of the secondary sheath of the sperm bundle are provided. Lastly, the evolution of the Coccid group is discussed from a phylogenetic perspective based on sperm ultrastructure. © 2015. Source

Valboa G.,Centro Of Ricerca Per Lagrobiologia E La Pedologia Crea Abp | Lagomarsino A.,Centro Of Ricerca Per Lagrobiologia E La Pedologia Crea Abp | Brandi G.,Centro Of Ricerca Per Lagrobiologia E La Pedologia Crea Abp | Agnelli A.E.,Centro Of Ricerca Per Lagrobiologia E La Pedologia Crea Abp | And 4 more authors.
Soil and Tillage Research | Year: 2015

Tillage practices have a major effect on soil C storage and cropping sustainability, due to their impact on soil aggregation, organic residue decomposition rate, OC dynamics, microbial abundance and diversity, N mineralization and nutrient availability. Our research was aimed at assessing the long term effects of different tillage treatments on soil organic matter (SOM) quantity and quality and its evolution with time, in a loam textured-soil from central Italy cultivated with continuous maize. The tillage treatments included a conventional tillage (DP) by mouldboard ploughing to 40. cm depth, a ripper subsoiling (RS) to 40-45. cm, a shallow tillage by mouldboard ploughing to 20. cm depth (SP) and minimum tillage to 10. cm by disk harrowing (DH). The soil was sampled in 1999 and 2011 (after 5 and 17 years from the beginning of the trial, respectively), at depth increments of 0-10, 10-20, 20-30 and 30-40. cm and analysed for total organic C (TOC), OC recalcitrant and labile fractions by chemical hydrolysis, total N, bulk density, aggregate stability and hydraulic conductivity.After 17 year of treatments, the different tillage systems did not affect the overall amount of OC stored in a 0-40. cm equivalent soil mass; nevertheless, they produced significant differences in soil OC vertical distribution along the soil profile and OC recalcitrance. Both DH and RS increased soil TOC in the surface layer, with predominance of labile OC under DH and recalcitrant OC under RS. Differently, DP caused a net loss of recalcitrant OC, probably due to a detrimental impact on soil aggregate stability and, subsequently, on SOM physical protection. RS showed the largest potential for OC sequestration in stable form in the considered agroecosystem. © 2015. Source

Discover hidden collaborations