Patterns of Root Colonization in Epacridaceous Plants Collected from Different Sites

Root colonization was studied in ten species of the Epacridaceaeat three sites in Victoria by morphological and cross-inoculationexperiments. The sites and genera chosen were Cranbourne [Epacrisimpressa Labill. andLeucopogon ericoides(Smith) R. Br.] andRye [L. parviflorus(Andrews) Lindley] on the Mornington Peninsula,and the Grampians[Astroloma conostephioides(Sond.) Benth.,A.humifusum(Cav.) R. Br.,A pinifolium(R. Br.) Benth,Brachylomadaphnoides(Smith) Benth.,E. impressa, E. impressavar.grandifloraBenth.andStyphelia adscendensR. Br.] in western Victoria. For morphologicalstudies, samples of roots from each species at each site werecleared and stained and examined microscopically. For cross-inoculationstudies, cuttings from each site were struck in potting mediuminoculated with soil from the same and other sites. The ericoidmycorrhizae in the roots of plants found at or grown in Cranbourneand Rye soils were similar. Both were significantly differentfrom the internal hyphae found in the roots of plants foundat or grown in Grampians soils, which were three times largerin diameter and formed dense coils which filled the host celland invaded adjacent epidermal cells. This suggests that morethan one fungus is involved in the relationships, that the MorningtonPeninsula sites had a different fungus from the Grampians siteand that host specificity is low. Vesicular structures werealso found commonly on plants at the Grampians site, in contrastwith other sites. Epacridaceae; root; fungus; mycorrhiza; morphology; inoculation     

Experimental and calculated circular dichroism spectra of monoaza[5]helicenes

Circular dichroism (CD) spectra have been measured in the range of 400-200 nm on CH₃OH solutions of both enantiomers for the almost complete series of monoaza[5]helicenes, namely the molecules where the hetero N atom occupies positions 1, 3, 4, 5, 6, and 7, respectively (the 2 isomer is missing due to difficulties in the synthesis). CD spectra recorded at controlled room temperature allow one to define precise racemization rates, that are nicely interpreted on the basis of DFT molecular orbital calculations. Time-dependent DFT methods provide us with calculated CD and UV spectra, that are compared with the corresponding experimental data. We discuss the role of the N atom in determining the height of the racemization barrier and in shaping the appearance of the CD spectra.     

Pattern diversity analysis of a clearing in a Quercus cerris wood

Linear transects were used to examine the spatial structure of the vegetation in a clearing in a Quercus cerris wood in Central Italy. A grassland-margin-shrubland-woodland gradient was identified.Multivariate classification and ordination methods and pattern diversity analysis were used to detect both floristic variation and spatial organization. One of the transects shows a clear gradient of variation as a function of space, crossing the floristically and structurally most heterogeneous part of the clearing. For the detailed analysis of this transect a sectorization is achieved. Each sector is characterized according to its floristic types and to the internal spatial organization.The pieces of information derived from the different analyses were concordant. In particular, the validity of the floristic types in the qualification of the different forms of spatial organization is confirmed.     

Molecular phylogenetics at the population/species interface in cave spiders of the southern Appalachians (Araneae:Nesticidae:Nesticus)

This paper focuses on the relationship between population genetic structure and speciation mechanisms in a monophyletic species group of Appalachian cave spiders (Nesticus). Using mtDNA sequence data gathered from 256 individuals, I analyzed patterns of genetic variation within and between populations for three pairs of closely related sister species. Each sister-pair comparison involves taxa with differing distributional and ecological attributes; if these ecological attributes are reflected in basic demographic differences, then speciation might proceed differently across these sister taxa comparisons. Both frequency-based and gene tree analyses reveal that the genetic structure of the Nesticus species studied is characterized by similar and essentially complete population subdivision, regardless of differences in general ecology. These findings contrast with results of prior genetic studies of cave-dwelling arthropods that have typically revealed variation in population structure corresponding to differences in general ecology. Species fragmentation through both extrinsic and intrinsic evolutionary forces has resulted in discrete, perhaps independent, populations within morphologically defined species. Large sequence divergence values observed between populations suggest that this independence may extend well into the past. These patterns of mtDNA genealogical structure and divergence imply that species as morphological lineages are currently more inclusive than basal evolutionary or phylogenetic units, a suggestion that has important implications for the study of speciation mechanisms.      

Prostaglandins in squamous cell carcinoma of the larynx: tumor and peritumor synthesis

Prostaglandin (PG) E2, 6ketoPGF1 alpha and Thromboxane B2 (TxB2) production by the tumor, peritumor and control tissue were investigated in specimens from patients (n = 11) with squamous cell carcinoma of the larynx, in relation to the extension and infiltration of the neoplasm and to the presence of inflammation, fibrosis and necrosis. In all specimens detectable amounts of 6ketoPGF1+ and TxB2 were found, but the predominant metabolite was PGE2. No differences in the levels of TxB2 and 6ketoPGF1 alpha were observed, but the only patient with lymphnodal involvement showed the lowest levels of 6ketoPGF1 alpha both in tumor and peritumor tissue. Higher amounts (p less than 0.05) of PGE2 were synthesized by peritumor tissues in comparison to control mucosa and tumor tissue independently of the occurrence of reactive infiltration. PGs synthesis did not correlate with inflammation, fibrosis, necrosis or staging of the neoplasm. However the two cases in stage T4 showed PGE2 generation at the highest levels both in neoplastic and perineoplastic tissue. These findings indicate that in squamous cell carcinoma of the larynx an increased production of PGE2 occurs, stemming not only from inflammatory cells but at least in part from neoplastic cells. This suggests that the study of arachidonic acid metabolism may contribute to characterization of the primary cancer and lead to better understanding of the mechanisms of tumor growth and diffusion.