The role of epiphytism in architecture and evolutionary constraint within mycorrhizal networks of tropical orchids

Characterizing the architecture of bipartite networks is increasingly used as a framework to study biotic interactions within their ecological context and to assess the extent to which evolutionary constraint shape them. Orchid mycorrhizal symbioses are particularly interesting as they are viewed as more beneficial for plants than for fungi, a situation expected to result in an asymmetry of biological constraint. This study addressed the architecture and phylogenetic constraint in these associations in tropical context. We identified a bipartite network including 73 orchid species and 95 taxonomic units of mycorrhizal fungi across the natural habitats of Reunion Island. Unlike some recent evidence for nestedness in mycorrhizal symbioses, we found a highly modular architecture that largely reflected an ecological barrier between epiphytic and terrestrial subnetworks. By testing for phylogenetic signal, the overall signal was stronger for both partners in the epiphytic subnetwork. Moreover, in the subnetwork of epiphytic angraecoid orchids, the signal in orchid phylogeny was stronger than the signal in fungal phylogeny. Epiphytic associations are therefore more conservative and may co‐evolve more than terrestrial ones. We suggest that such tighter phylogenetic specialization may have been driven by stressful life conditions in the epiphytic niches. In addition to paralleling recent insights into mycorrhizal networks, this study furthermore provides support for epiphytism as a major factor affecting ecological assemblage and evolutionary constraint in tropical mycorrhizal symbioses.     

The mitochondrial and nuclear genetic structure of Myotis capaccinii (Chiroptera: Vespertilionidae) in the Eurasian transition, and its taxonomic implications

Allopatric isolation in glacial refugia has caused differentiation and speciation in many taxa globally. In this study, we investigated the nuclear and mitochondrial genetic differentiation of the long fingered bat, Myotis capaccinii during the ice ages in south-eastern Europe and Anatolia. The mitochondrial DNA (mtDNA) analyses indicated a suture zone similar to those recorded in other animal species, including bats, suggesting the association of more than one refugium with the region. Contrary to most of the other species where a suture zone was seen in Anatolia, for M. capaccinii the geographical location of the genetic break was in south-eastern Europe. This mitochondrial differentiation was not reflected in the nuclear microsatellites, however, suggesting that the lack of contact during the ice ages did not result in reproductive isolation. Hence taxonomically, the two mitochondrial clades cannot be treated as separate species.     

S-100 protein in human lung neuroendocrine neoplasms. Immunohistochemical study of 14 cases and review of the literature

A group of lung neuroendocrine (NE) neoplasms are investigated in view of the possible presence of S-100 protein immunoreactivity in their cells. The selected tumours were classified according to Gould et al. (1983a) and Mosca et al. (1985). They comprise 5 carcinoids, 3 neuroendocrine carcinomas of the well-differentiated type, or peripheral carcinoids, 5 neuroendocrine carcinomas of the intermediate cell type, or intermediate-cell, poorly differentiated carcinomas, 3 neuroendocrine carcinomas of the microcytoma type, or small cell carcinomas-SCC and a nodal metastasis of microcytoma. All but 2 tumours were immunoreactive for neuron specific enolase (NSE). Few S-100 immunoreactive cells were detected in 4 out of 5 carcinoids, in 1 out of 3 peripheral carcinoids, in 4 out of 5 poorly differentiated carcinomas and in the 3 microcytomas examined. No S-100 positive cells were found in the SCC's nodal metastasis. The S-100 immunolabelled cells can be interpreted as dendritic reticulum cells migrating through the tumours. However, in one case of typical carcinoid, abundant S-100 positive cells were detected: their stellate morphology and their intimate relation with neoplastic cells suggest that they are part of the neoplasia as a sort of satellite cell.     

Pericentric inversion of chromosome 19 in three families

Summary Pericentric inversion of chromosome 19 has been found in several members of three unrelated families from a restricted geographical region. In one of the families, an additional pericentric inversion of chromosome 9 was observed. Reproductive problems, multiple abortions in two families and a neonatal death in the third, were present. A review of previously described cases is included, and the genetic risk connected with this type of rearrangement is also discussed.     

Influence of plant extracts on the metabolic activity of the yeast Saccharomyces cerevisiae 39]

Addition to the nutrient medium of the extracts of camomile, nettle, mint, or Saint-John's-wort to a concentration of 0.5-4% was established to activate the yeast growth. The maximum effect was recorded on the addition of the extracts to the poor "water" medium. The extracts of camomile and Saint-John's-wort were shown to inhibit the alcohol dehydrogenase activity of the yeast cells, whereas the extracts of nettle and mint increased the activity of this enzyme by 62-70%.     

Persistence of the control of the fluctuations of heart rate in the anesthetized and pithed adult rat. Effect of enteraminergic drugs]

Spontaneous fluctuations in heart rate were analyzed by spectral analysis in the ether anesthetized and pithed adult rat. In order to investigate the changes in the spectral pattern of the fluctuations, the selective 5HT-2 and -3 isoreceptor blockers ritanserin and BRL 43694A were used. In both the experimental conditions, ritanserin blockade led to dose-dependent increased fluctuations in HR low and high frequencies. In both the anesthetized and pithed rats, the low frequency range HR fluctuations were drastically reduced by BRL 43694A.     

Evaluation of nucleolar organizer region-associated proteins in endometrial pathology.

In the current study the argyrophil staining technique for NOR proteins (Ag-NORs) has been performed on cases of different endometrial lesions, trying to find an aid in differentiating atypical hyperplasia from well differentiated carcinoma in biopsy specimens. We conclude that the Ag-NOR count, even though in endometrial carcinoma is significantly exceeding that of atypical hyperplastic endometrium, could be a misleading discriminator, because of a wide overlap of values in individual cases.