A new late Westphalian fossil marattialean fern from Nova Scotia

Sydneia manleyi gen. et sp. nov. is based on part of a fertile frond from the upper Westphalian D of the Sydney Coalfield, Nova Scotia, Canada. It has small synangia composed of laterally fused sporangia that are elongate and with a circular cross-section. The sporangia yielded variably sized monolete and trilete spores with laevigate and microspinate ornamentation; intermediate forms were also observed. The spores can be correlated with the sporae dispersae species Latosporites minutus , Punctatosporites oculus and Laevigatosporites minimus . Size distribution of the spores is variable and highly skewed, suggesting heterogeneity of the spores within the sporangium. Spore ultrastructure indicates that the fossil is part of a fern, and the morphology of the spores and synangia indicate marattialean affinities.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 199–212.     

Host-associated speciation in the coral barnacle Wanella milleporae (Cirripedia: Pyrgomatidae) inhabiting the Millepora coral

Speciation by host shift is a common phenomenon observed in many symbiotic animals. The symbiont–host interaction is highly dynamic, but it is poorly documented in the marine realm. In the present study, we examined the genetic and morphological differentiation of the coral barnacle Wanella milleporae (obligate to fire corals) collected from four different Millepora host species in Taiwan to investigate the host specificity of this barnacle. Phylogenetic analysis of mitochondrial COI gene for 241 individuals of Wanella revealed five distinct clades, whose sequence divergences are comparable to values between other cogeneric barnacle species. The five clades also differ in shell and opercular plate morphology and colour. Genetic and morphological differentiations together strongly suggest the presence of cryptic species. Although the five clades do not display species-level host specificity, they showed a significant difference in preference on host growth form. Clades 1 and 2 were predominantly found on encrusting Millepora exaesa and Millepora platyphylla , while clades 3, 4 and 5 live exclusively on branching-form fire corals Millepora dichotoma and Millepora tenella . Phylogeny inferred from the combined mitochondrial COI, 16S and 12S (2182 bp) analysis suggests the division of the five clades into two major lineages congruent with the morphology of the host coral. Multiple independent invasions to the same form of host and subsequent speciation are evident in the Red Sea and Taiwan. Our results indicate that ecological/sympatric speciation could occur in marine symbiotic invertebrates through host shift and specialization. It appears that, as in their terrestrial counterparts, host–symbiont radiations in the marine realm are more prevalent than we expected and thus warrant further investigation.     

Dosimetric study of Hounsfield number correction effect in areas influenced by contrast product in lungs case

BackgroundThe aim of the study was dosimetric effect quantification of exclusive computed tomography (CT) use with an intravenous (IV) contrast agent (CA ), on dose distribution of 3D-CRT treatment plans for lung cancer. Furthermore, dosimetric advantage investigation of manually contrast-enhanced region overriding, especially the heart.Materials and methodsTen patients with lung cancer were considered. For each patient two planning CT sets were initially taken with and without CA. Treatment planning were optimized based on CT scans without CA. All plans were copied and recomputed on scans with CA. In addition, scans with IV contrast were copied and density correction was performed for heart contrast enhanced. Same plans were copied and replaced to undo dose calculation errors that may be caused by CA. Eventually, dosimetric evaluations based on dose volume histograms (DVHs) of planning target volumes (PTV) and organs at-risk were studied and analyzed using the Wilcoxon’s signed rank test.ResultsThere is no statistically significant difference in dose calculation for the PTV maximum, mean, minimum doses, spinal cord maximum doses and lung volumes that received 20 and 30 Gy, between planes calculated with and without contrast scans (p > 0.05) and also for contrast scan, with manual regions overriding.ConclusionsDose difference caused by the contrast agent is negligible and not significant. Therefore, there is no justification to perform two scans, and using an IV contrast enhanced scan for dose calculation is sufficient.     

First morphogenetic identification of <i>Fusarium solani</i> isolated from orange fruit in Egypt

Losses due to postharvest decay may occur at any time during postharvest handling, from harvest to consumption affecting the produce quality and quantity. Accurate identification of the pathogen causing postharvest disease is essential to the selection of an appropriate disease control approach. Nine isolates of Fusarium recovered from orange fruit were identified as Fusarium solani. The fungus is involved with fruit decay. The obtained cultures were purified and grown on potato-dextrose agar (PDA), malt yeast agar (MYA), and Czapek's nutrient media (CNM) under light for identification. A pathogenicity test was carried out to fulfil Koch's postulates. The pathogen could only enter ripe orange fruit through wounds and cracks causing the rot disease. The identification of the fungal isolates was confirmed to be F. solani by DNA sequencing, which was 99 to 100% homologous to those deposited in the Gen- Bank. The identity of nine fungal isolates was confirmed to be F. solani by DNA sequencing of the internal transcribed spacer (ITS) rDNA region (GenBank Accession Nos. DQ486874 to DQ486881 and KC758879). To our knowledge, this is the first morphogenetic identification of F. solani isolated from orange fruit in Egypt.     

Stereoselective synthesis of enantiopure N-substituted pyrrolidin-2,5-dione derivatives by 1,3-dipolar cycloaddition and assessment of their in vitro antioxidant and antibacterial activities

1,3-Dipolar cycloaddition between a chiral nitrone and N-substituted maleimides afforded unprecedented enantiopure spiro-fused heterocycles in good yields with a high enantio- and diastereoselectivity. The reaction was taking place on the less hindered face of the nitrone. The obtaining heterocycles were screened for their in vitro antioxidant properties and the results revealed that the potent antioxidant activity was generally recorded to compounds (3g) and (3e). The in vitro antibacterial activities of these two compounds were also investigated and the results demonstrated the strongest potential of compound (3g) against all the tested bacteria. Molecular properties were analyzed and showed good oral drug candidate like properties and that could be exploited as a potential antioxidant and antimicrobial agent. Finally, the preliminary results obtained from this investigation attempted to clarify if the structurally different side chains of active compounds interfere with their biological properties.     

Genetic differentiation,hybridization and adaptive divergence in two subspecies of the acorn barnacle Tetraclita japonica in the northwestern Pacific

Two acorn barnacles, Tetraclita japonica japonica and Tetraclita japonica formosana, have been recently reclassified as two subspecies, because they are morphologically similar and genetically indistinguishable in mitochondrial DNA sequences. The two barnacles are distinguishable by parietes colour and exhibit parapatric distributions, coexisting in Japan, where T. j. formosana is very low in abundance. Here we investigated the genetic differentiation between the subspecies using 209 polymorphic amplified fragment length polymorphism markers and 341 individuals from 12 locations. The subspecies are genetically highly differentiated (Φ_CT = 0.267). Bayesian analysis and principal component analysis indicate the presence of hybrids in T. j. formosana samples from Japan. Strong differentiation between the northern and southern populations of T. j. japonica was revealed, and a break between Taiwan and Okinawa was also found in T. j. formosana. The differentiation between the two taxa at individual loci does not deviate from neutral expectation, suggesting that the oceanographic pattern which restricts larval dispersal is a more important factor than divergent selection in maintaining genetic and phenotypic differentiation. The T. j. formosana in Japan are probably recent migrants from Okinawa, and their presence in Japan may represent a poleward range shift driven by global warming. This promotes hybridization and might lead to a breakdown of the boundary between the subspecies. However, both local adaptation and larval dispersal are crucial in determining the population structure within each subspecies. Our study provides new insights into the interplay of local adaptation and dispersal in determining the distribution and genetic structure of intertidal biota and the biogeography of the northwestern Pacific.     

Scl binds to primed enhancers in mesoderm to regulate hematopoietic and cardiac fate divergence

Scl/Tal1 confers hemogenic competence and prevents ectopic cardiomyogenesis in embryonic endothelium by unknown mechanisms. We discovered that Scl binds to hematopoietic and cardiac enhancers that become epigenetically primed in multipotent cardiovascular mesoderm, to regulate the divergence of hematopoietic and cardiac lineages. Scl does not act as a pioneer factor but rather exploits a pre‐established epigenetic landscape. As the blood lineage emerges, Scl binding and active epigenetic modifications are sustained in hematopoietic enhancers, whereas cardiac enhancers are decommissioned by removal of active epigenetic marks. Our data suggest that, rather than recruiting corepressors to enhancers, Scl prevents ectopic cardiogenesis by occupying enhancers that cardiac factors, such as Gata4 and Hand1, use for gene activation. Although hematopoietic Gata factors bind with Scl to both activated and repressed genes, they are dispensable for cardiac repression, but necessary for activating genes that enable hematopoietic stem/progenitor cell development. These results suggest that a unique subset of enhancers in lineage‐specific genes that are accessible for regulators of opposing fates during the time of the fate decision provide a platform where the divergence of mutually exclusive fates is orchestrated.