Microtubular Systems of Paramecium in Division: Pattern of Cytospindle Assembly

The pattern of cytospindle assembly and the modifications of the microtubular cytoplasmic network during division of Paramecium are studied by means of indirect immunofluorescence. The assembly of cytospindle starts at two independent areas placed respectively around the proter's and opisthe's buccal overture. The moment of the microtubule bundles’appearance depends on their distance from the buccal opening, with those closest appearing 1st. The existence of microtubule organizing centers that act transiently during division of Paramecium is discussed.     

TWO NEW SPECIES OF THE GENUS ISLAMIA RADOMAN, 1973 FROM ITALIAN ISLANDS (PROSOBRANCHIA, HYDROBIIDAE)

Two new Italian species of the genus Islamia (Prosobranchia:Hydrobiidae), one living in eastern Sicily (I. cianensis), andone on Elba Island (Tuscan Archipelago, Italy) (I. gaiteri)are described. The two species are distinguished on the basisof shell and anatomical characters, mainly those of the malegenitalia. I. cianesis n. sp. is characterized by a valvatoidshell and a penial lobe with internal band of glandular tissuenot distinct in its lower portion from the penis body but bulgingapically as a small knob. I. gaiteri n. sp. is characterizedby a planispiral shell and a small lateral penial lobe withoutinternal glandular tissue. (Received 20 December 1993; accepted 27 June 1994)     

Strontium stratigraphy of the Burdigalian transgression in the Western Mediterranean

Brandano, M. & Policicchio, G. 2011: Strontium stratigraphy of the Burdigalian transgression in the Western Mediterranean. Lethaia, Vol. 45, pp. 315–328. A ⁸⁷Sr/⁸⁶Sr analysis of selected pectinid shells has been performed to refine the stratigraphical framework of the Burdigalian transgressive event. Samples were collected from shallow water successions of the Western Mediterranean area (North‐Eastern Sardinia, Southern Corsica, Central Apennines). The Western Mediterranean is the result of the interaction between the European and the African plates. Sardinia and Corsica were extended and rifted apart from the Iberian Peninsula during the opening of the Liguro‐Provencal basin, between 30 and 15 Ma. In the outcrops of Northern Sardinia and Southern Corsica, Burdigalian deposits nonconformably overlie Varisican granites. In the central Apennines the Burdigalian deposits paraconformably overlie the Cretaceous platform. These are transgressive deposits, characterized by the presence of Miogypsina globulina, which points out early to middle Burdigalian age. The Sr isotope ages indicate that marine transgression in Northern Sardina and Southern Corsica took place between 18.6 and 18.3 Ma, which could correspond to the eustatic sea level rise of the Bur3 third‐order sequence. In the Central Apennines the Burdigalian transgression was anticipated (18.8 Ma) by subsidence input linked to the eastward migration of the orogenic system. This input allowed the Miocene carbonate ramp to develop on the Cretaceous platform substrate, while successive eustatic rise controlled the evolution of the stratigraphical architecture. The following regressive phase is recorded in both the Apennine and Corsica successions. The end of this phase is dated between 17.6 and 17.5 Ma and corresponds to sea level drop corresponding to the occurrence of the Mi 1b event. □Burdigalian, pectinids, strontium stratigraphy, transgression, Western Mediterranean     

Testing the role of male–male competition in the evolution of sexual dimorphism: a comparison between two species of porcelain crabs

Theory predicts marked sexual dimorphism in terms of body size and body structures used as weapons (e.g. chelipeds) in gonochoric species with intense male sexual competition for receptive females and reduced or no sexual dimorphism in species where competition among males is trivial. We tested this hypothesis using a pair of closely‐related species of symbiotic porcelain crabs as a model. In one species that inhabits sea anemones solitarily, competition among males for receptive females is unimportant. In a second species that dwells as dense aggregations on sea urchins, male–male competition for sexual partners is recurrent. We expected considerable sexual dimorphism in body size and weaponry in the urchin‐dwelling crab and reduced sexual dimorphism in the anemone‐dwelling crab. In agreement with expectations, in the urchin‐dwelling crab, male body size was, on average, larger than that of females and males invested considerably more to cheliped length than females. Also supporting theoretical considerations, in the anemone‐dwelling crab, sexual dimorphism in terms of body size was not detected and differences between the sexes in investment to cheliped length were minor. Interestingly, chelipeds were more developed both in males and females of the anemone‐dwelling crab than in the urchin‐dwelling crab as a result of the importance of these structures for monopolization of their naturally scarce anemone hosts. Another difference between the studied species was the existence of two clearly distinguishable ontogenetic phases in males of the urchin‐dwelling crab but not in males of the anemone‐dwelling crab. Whether the two different male morphs display different male reproductive strategies in the urchin‐dwelling crab remains to be addressed. Other conditions that might additionally explain the observed differences in sexual dimorphism (e.g. female mate choice) between the studied species remain to be explored. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 548–558.     

OUTLINING ETHICAL ISSUES IN NANOTECHNOLOGIES

Nanotechnologies are an expression of the human ability to control and manipulate matter on a very small scale. Their use will enable an even and constant monitoring of human organisms, in a new and perhaps less invasive way. Debates at all levels – national, European and international – have pointed out the common difficulty of giving a complete, clear definition of nanotechnologies. This is primarily due to the variety of their components, to the fact that there is not just one technology but several.
The most significant medical applications of nanotechnologies are in the diagnostic and the therapeutic fields, eg biosensors and molecular imaging, providing diagnosis and drug delivery with no invasive methods involved.
Like any other emerging field, such technologies imply new possibilities for improving health but, on the other hand, they are still at an experimental stage and therefore should be implemented under rigorous safety testing before going on general release. For this purpose, the ethical, legal and social implications (ELSI) of nanotechnologies have been elaborated by study groups, in order to develop solutions before the results of the tests are diffused into medical practice.
The aim of this paper is to define some of the ethical issues concerning biomedical applications and to evaluate whether there is a need for new or additional guidelines and regulations.     

cpFBPaseII, a novel redox-independent chloroplastic isoform of fructose-1,6-bisphosphatase

A full-length FBPase cDNA has been isolated from Fragaria  ×  ananassa (strawberry) corresponding to a novel putative chloroplastic FBPase but lacking the regulatory redox domain, a characteristic of the plastidial isoenzyme (cpFBPaseI). Another outstanding feature of this novel isoform, called cpFBPaseII, is the absence of the canonical active site. Enzymatic assays with cpFBPaseII evidenced clear Mg²⁺-dependent FBPase activity and a K _m for fructose-1,6-bisphosphate (FBP) of 1.3 m m . Immunolocalization experiments and chloroplast isolation confirmed that the new isoenzyme is located in the stroma. Nevertheless, unlike cpFBPaseI, which is redox activated, cpFBPaseII did not increase its activity in the presence of either DTT or thioredoxin f (TRX f ) and is resistant to H₂O₂ inactivation. Additionally, the novel isoform was able to complement the growth deficiency of the yeast FBP1 deletion fed with a non-fermentable carbon source. Furthermore, orthologues are restricted to land plants, suggesting that cpFBPaseII is a novel and an intriguing chloroplastic FBPase that emerged late in the evolution of photosynthetic organisms, possibly because of a pressing need of land plants.     

Identification of virulence genes in Fusarium oxysporum f. sp. lycopersici by large-scale transposon tagging

Forward genetic screens are efficient tools for the dissection of complex biological processes, such as fungal pathogenicity. A transposon tagging system was developed in the vascular wilt fungus Fusarium oxysporum f. sp. lycopersici by inserting the novel modified impala element imp160::gfp upstream of the Aspergillus nidulans niaD gene, followed by transactivation with a constitutively expressed transposase. A collection of 2072 Nia⁺ revertants was obtained from reporter strain T12 and screened for alterations in virulence, using a rapid assay for invasive growth on apple slices. Seven strains exhibited reduced virulence on both apple slices and intact tomato plants. Five of these were true revertants showing the re-insertion of imp160::gfp within or upstream of predicted coding regions, whereas the other two showed either excision without re-insertion or no excision. Linkage between imp160::gfp insertion and virulence phenotype was determined in four transposon-tagged loci using targeted deletion in the wild-type strain. Knockout mutants in one of the genes, FOXG_00016 , displayed significantly reduced virulence, and complementation of the original revertant with the wild-type FOXG_00016 allele fully restored virulence. FOXG_00016 has homology to the velvet gene family of A. nidulans . The high rate of untagged virulence mutations in the T12 reporter strain appears to be associated with increased genetic instability, possibly as a result of the transactivation of endogenous transposable elements by the constitutively expressed transposase.     

The powdery mildew fungus Podosphaera fusca (synonym Podosphaera xanthii), a constant threat to cucurbits

Numerous vegetable crops are susceptible to powdery mildew, but cucurbits are arguably the group most severely affected. Podosphaera fusca (synonym Podosphaera xanthii ) is the main causal agent of cucurbit powdery mildew and one of the most important limiting factors for cucurbit production worldwide. Although great efforts have been invested in disease control, by contrast, many basic aspects of the biology of P. fusca remain unknown.
Taxonomy: Podosphaera fusca (Fr.) Braun & Shishkoff. Kingdom Fungi; Phylum Ascomycota; Subdivision Pezizomycotina; Class Leotiomycetes; Order Erysiphales; Family Erysiphaceae; genus Podosphaera ; species fusca.
Identification: Superficial persistent mycelium. Conidia in chains, hyaline, ellipsoid to ovoid or doliform, about 24–40 × 15–22 µm, with cylindrical or cone-shaped fibrosin bodies, which often germinate from a lateral face and produce a broad, clavate germ tube and cylindrical foot-cells. Unbranched erect conidiophores. Cleistothecia globose, mostly 70–100 µm in diameter, dark brown/black. One ascus per cleistothecium with eight ascospores.
Host range: Angiosperm species that include several families, such as Asteracea, Cucurbitaceae, Lamiaceae, Scrophulariaceae, Solanaceae and Verbenaceae.
Disease symptoms: White colonies develop on leaf surfaces, petioles and stems. Under favourable environmental conditions, the colonies coalesce and the host tissue becomes chlorotic and usually senesces early.
Control: Chemical control and the use of resistant cultivars. Resistance has been documented in populations of P. fusca to some of the chemicals registered for control.     

Seed dispersal and population structure in Vriesea gigantea,a bromeliad from the Brazilian Atlantic Rainforest

Seed dispersal, population structure and the mating system of plant species can have great consequences on the genetic structure of populations. Vriesea gigantea is a bromeliad from southeastern Brazil which is self‐compatible and pollinator dependent for fruit set. Its populations are fertile in terms of the production of flowers, pollen, fruits and seeds. To assess the importance of seed supply for gene flow, colonization and distribution of adult individuals, the seed dispersal and population structure of V. gigantea were studied. Seeds are dispersed over short distances; most seeds land close to the mother plant. This pattern coincides with the reported aggregate distribution of bromeliad seedlings. Population structure results showed high seedling recruitment, because 51.3% developed into adults, although few juveniles reached this stage. This result is different from that for other bromeliad species from different habitat conditions. Seed dispersal and population structural patterns are consistent with previous molecular studies, revealing that V. gigantea populations are genetically structured, with low gene flow and a moderate outcrossing rate. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 317–325.