Vitex agnus‐castus cannot be used as trap plant for the vector Hyalesthes obsoletus to prevent infections by ‘Candidatus Phytoplasma solani’ in northern Italian vineyards: Experimental evidence

Bois noir (BN), the most prevalent disease of the grapevine yellows complex, causes considerable yield loss in vineyards. BN is associated with phytoplasma strains of the species ‘Candidatus Phytoplasma solani’ (taxonomic subgroup 16SrXII‐A). In Europe, the BN phytoplasma is transmitted to grapevine mainly by Hyalesthes obsoletus, a polyphagous cixiid completing its life cycle on stinging nettle and field bindweed. As a result of the complexity of BN epidemiology, no effective control strategies have been developed. In previous studies conducted in the eastern Mediterranean coast of Israel, chaste tree (Vitex agnus‐castus) was found to be the preferred host plant of H. obsoletus but did not harbour BN phytoplasma. Thus, a ‘push and pull’ strategy was suggested based on the fact that chaste tree plants located at vineyard borders was an effective trap plant for H. obsoletus adults. However, in other studies carried out in the eastern Adriatic coast of Montenegro, chaste tree was found to be a key source plant for BN phytoplasma transmission to grapevine. This study aimed to investigate (i) the interaction between chaste tree and H. obsoletus through survival, attractiveness and oviposition experiments conducted comparing the behaviour of H. obsoletus in chaste tree versus stinging nettle and grapevine and (ii) the capability of chaste tree to harbor ‘Ca. P. solani’ in northern Italy through transmission trials. H. obsoletus adults were found to survive on chaste tree and grapevine over a 1 week period and prefer chaste tree to grapevine. Moreover, H. obsoletus produced eggs and overwintered as nymphs on chaste tree, even if at a lesser extent than on stinging nettle. H. obsoletus originating from nettle was found able to transmit ‘Ca. P. solani’ to chaste tree (2 plants of 16 were found infected by the BN phytoplasma strain St5 identified in H. obsoletus specimens). These results increased our knowledge about the role of Vitex agnus‐castus as host plant of H. obsoletus and BN phytoplasma in northern Italy and do not recommend considering chaste tree as trap plant at vineyard borders.     

Validation of a one-step PCR assay for the molecular identification of Echinococcus granulosus sensu stricto G1–G3 genotype

Molecular Biology Reports - The Italian National Reference Center for Echinococcosis (CeNRE, Sassari, Italy) set up a diagnostic protocol of “one-step-PCR” useful for the detection of...     

Analysis of the reproductive cycle of female wild marble trout <Emphasis Type="Italic">Salmo marmoratus</Emphasis> in a prealpine brook of the Soča River basin (Northeast Italy)

The reproductive cycle of female wild marble trout Salmo marmoratus was studied in a prealpine watercourse (Northeast Italy). Gonadosomatic index, oocyte growth and plasma levels of 17β-oestradiol and testosterone were bimonthly measured during one year to obtain a detailed dataset and to gain useful tools for the identification of the reproductive stage without impact for the species. Monitored features showed significant variations during the study period: gonadosomatic index and oocyte size increased slightly but significantly during the first part of the cycle (from February to June), while steroid levels remained quite constant; for all parameters, major increases were highlighted between August and the spawning season (which occurred from the middle of November to the middle of December). Ranges and trends observed for gonadosomatic index (from 0.87 ± 0.41% to 10.91 ± 3.37%) and oocyte diameter (from 0.692 ± 0.031 mm to 4.624 ± 0.208 mm) were generally in agreement with literature regarding salmonids, while plasma levels of 17β-oestradiol (from 0.214 ± 0.015 ng ml^?1 to 78.090 ± 23.882 ng ml^?1) and testosterone (from 0.327 ± 0.086 ng ml^?1 to 71.800 ± 29.406 ng ml^?1) showed wider ranges. A strong non-linear relationship was found between oocyte size and 17β-oestradiol plasma concentration (r ² = 0.890) and especially between oocyte size and testosterone plasma concentration (r ² = 0.947). This last relationship could likely be used to obtain information relative to the gonadal development, especially in the case of an endangered species like Salmo marmoratus, which needs non-invasive tools for management.     

The intrinsically disordered linker of E. coli SSB is critical for the release from single‐stranded DNA

The Escherichia coli single stranded DNA binding protein (SSB) is crucial for DNA replication, recombination and repair. Within each process, it has two seemingly disparate roles: it stabilizes single‐stranded DNA (ssDNA) intermediates generated during DNA processing and, forms complexes with a group of proteins known as the SSB‐interactome. Key to both roles is the C‐terminal, one‐third of the protein, in particular the intrinsically disordered linker (IDL). Previously, they have shown using a series of linker deletion mutants that the IDL links both ssDNA and target protein binding by mediating interactions with the oligosaccharide/oligonucleotide binding fold in the target. In this study, they examine the role of the linker region in SSB function in a variety of DNA metabolic processes in vitro. Using the same linker mutants, the results show that in addition to association reactions (either DNA or protein), the IDL is critical for the release of SSB from DNA. This release can be under conditions of ssDNA competition or active displacement by a DNA helicase or recombinase. Consistent with their previous work these results indicate that SSB linker mutants are defective for SSB–SSB interactions, and when the IDL is removed a terminal SSB–DNA complex results. Formation of this complex inhibits downstream processing of DNA by helicases such as RecG or PriA as well as recombination, mediated by RecA. A model, based on the evidence herein, is presented to explain how the IDL acts in SSB function.     

From single muscle fiber to whole muscle mechanics: a finite element model of a muscle bundle with fast and slow fibers

Muscles exhibit highly complex, multi-scale architecture with thousands of muscle fibers, each with different properties, interacting with each other and surrounding connective structures. Consequently, the results of single-fiber experiments are scarcely linked to the macroscopic or whole muscle behavior. This is especially true for human muscles where it would be important to understand of how skeletal muscles disorders affect patients’ life. In this work, we developed a mathematical model to study how fast and slow muscle fibers, well characterized in single-fiber experiments, work and generate together force and displacement in muscle bundles. We characterized the parameters of a Hill-type model, using experimental data on fast and slow single human muscle fibers, and comparing experimental data with numerical simulations obtained from finite element (FE) models of single fibers. Then, we developed a FE model of a bundle of 19 fibers, based on an immunohistochemically stained cross section of human diaphragm and including the corresponding properties of each slow or fast fiber. Simulations of isotonic contractions of the bundle model allowed the generation of its apparent force–velocity relationship. Although close to the average of the force–velocity curves of fast and slow fibers, the bundle curve deviates substantially toward the fast fibers at low loads. We believe that the present model and the characterization of the force–velocity curve of a fiber bundle represents the starting point to link the single-fiber properties to those of whole muscle with FE application in phenomenological models of human muscles.     

Riodocea (Rubiaceae, Gardenieae), a new genus from the Brazilian Atlantic forest

The genusRiodocea is here described from material collected in the várzea forest of the Rio Doce Valley, northern Espírito Santo.Riodocea is a monotypic genus probably related to the Amazonian endemicKutchubaea. A line drawing shows general morphology and photomicrographs show pollen morphology ofRiodocea pulcherrima. Distribution maps ofRiodocea andKutchubaea are included. The valley of the Rio Doce is here included in the Bahian Hylaea, defined as a subregion of the Brazilian Atlantic forest. The connections between the Amazonian Hylaea and the Bahian Hylaea are discussed.     

Biodeterioration of ornamental marble statues in the Boboli Gardens (Florence, Italy)

The colonisation of ornamental marble statues in theBoboli Gardens of Florence (Italy) by photosyntheticmicro-organisms was investigated. The greenmicroalga Coccomyxa was the first colonizer ofnewly restored marble surfaces, appearing one yearafter the periodic cleaning and restoration of thestatues. Two years after restoration this alga gaverise to very thin green biofilms, with densitiesreaching about 3 × 10² cells cm^-2. Later,the biofilms were enriched by cyanobacterial forms,which became dominant. In about six years, aphotosynthetic microbial community, amounting to about3 × 10⁴ cells cm^-2, and structurally similarto that occurring on the unrestored statues wasdeveloped. This epilithic community showed amarked biodiversity; the main representative formsincluded Chroococcidiopsis, Leptolyngbya,Pleurocapsa, Coccomyxa and Apatococcus.Coccomyxa initiated the colonisation of themarble surfaces, favoured in this process by itsfacultative oligotrophic capacity and high cellsurface hydrophobicity, combined with tolerance ofhigh light intensity. The other investigated isolatedstrains did not show this set of features. Thesecretion of polysaccharidic substances and cellsurface hydrophobicity enhancing the capacity toadhere, favoured permanent colonisation of thecyanobacterial population. Indeed, the majority of thecyanobacterial strains (90%), were shown to besurrounded by exopolysaccharidic envelops, whichcontributed to the formation of stable microbialbiofilms, and possessed variable cell surfacehydrophobicity.     

Calcium elevation in sheep cumulus-oocyte complexes after luteinising hormone stimulation

We investigated Ca²⁺ levels in intact cumulus-oocyte complexes (COCs) on exposure to peak levels of luteinising hormone (LH). Specific preparations were used where cumulus corona cells were loaded with a membrane-permeant Ca²⁺-sensitive dye (FLUO-3AM), whereas the oocyte was injected directly with the nonpermeant form of the dye (FLUO-3). After exposure to LH, cumulus and corona radiata cells showed distinct rises in intracellular Ca²⁺ in 50–200 sec. The pattern of Ca²⁺ response varied in the different cells both for the duration of the transients and for their persistence. Interestingly, Ca²⁺ elevations were recorded in all the layers of the cumulus mass, including the innermost layer of corona cells, demonstrating the wide diffusion of LH receptors. Following the Ca²⁺ raise in somatic cells, an intracellular Ca²⁺ elevation also was recorded within the oocyte with a delay of 100–300 sec. The elevation started at the cortex of the oocyte and then spread all over the ooplasm. The addition of verapamil or manganese chloride did not prevent LH-induced Ca²⁺ elevation in the COC, whereas mechanical uncoupling of cumulus cells from the oocyte prevented any Ca²⁺ response within the oocyte. The results indicate that cumulus-corona cells are capable of transducing LH message by rising intracellular Ca²⁺ and show that this signal is rapidly transferred into the oocyte through gap junctions. This may result from the direct diffusion of Ca²⁺ or its putative releaser IP3 from cumulus cells to the oocyte. Mol. Reprod. Dev. 50:361–369, 1998. © 1998 Wiley-Liss, Inc.     

Oncogene alterations in primary,recurrent, and metastatic human bone tumors

We investigated the structure and the expression of various oncogenes in three of the most common human bone tumors—osteosarcoma (36 samples from 34 patients), giant cell tumor (10 patients), and chondrosarcoma (18 patients)—in an attempt to identify the genetic alterations associated with these malignancies. Alterations of RB and p53 were detected only in osteosarcomas. Alterations of c-myc, N-myc, and c-fos were detected in osteosarcomas and giant cell tumors. Ras alterations (H-ras, Ki-ras, N-ras) were rare. Chondrosarcomas did not contain any detectable genetic alterations. Our results suggest that alterations of c-myc, N-myc, and c-fos oncogenes occur in osteosarcomas, in addition to those previously described for the tumor suppressor genes RB and p53. Moreover, statistical analyses indicate that c-fos alterations occur more frequently in osteosarcoma patients with recurrent or metastatic disease. © 1996 Wiley-Liss, Inc.