Atypical development of Chaetomorpha antennina in culture (Cladophorales,Chlorophyta)

The green seaweed genus Chaetomorpha is characterized by unbranched filaments. Molecular phylogenetic data indicate that Chaetomorpha forms a clade that is nested in a paraphyletic assemblage of branched species (Cladophora). It follows that the unbranched condition is evolutionarily conserved and likely evolved early in the evolution of this clade. In this study we show that under laboratory culture conditions, the filaments of C. antennina frequently produce lateral branches, similar to Cladophora. Our results thus indicate that the unbranched thallus architecture is not entirely genetically constrained, but at least in part subject to morphological plasticity. Additionally, culture observations of C. antennina allowed a detailed study of rhizoidal development, which seems unique among Cladophorales.     

Diverse Responses to Vascular Disrupting Agent Combretastatin A4 Phosphate: A Comparative Study in Rats with Hepatic and Subcutaneous Tumor Allografts Using MRI Biomarkers,Microangiography, and Histopathology

OBJECTIVE: Differently located tumors of the same origin may exhibit diverse responses to the same therapeutics. To test this hypothesis, we compared the responses of rodent hepatic and subcutaneous engrafts of rhabdomyosarcoma-1 (R1) to a vascular disrupting agent Combretastatin A4 phosphate (CA4P). METHODS: Twelve WAG/Rij rats, each bearing three R1 implanted in the right and left hepatic lobes and subcutaneously in the thoracic region, received CA4P intravenously at 5 mg/kg (n = 6) or solvent (n = 6). Therapeutic responses were compared interindividually and intraindividually among tumors of different sites till 48 hours after injection using in vivo MRI, postmortem digital microangiography, and histopathology. RESULTS: MRI revealed that the subcutaneous tumors (STs) significantly increased in volume than hepatic tumors (HTs) 48 hours after CA4P (P < .05). Relative to vehicle controls and treated group at baseline, necrosis ratio, apparent diffusion coefficient, and enhancement ratio changed slightly with the STs but significantly with HTs (P < .05) after CA4P treatment. Vessel density derived from microangiography was significantly lower in STs compared to HTs without CA4P treatment. CA4P treatment resulted in decreased vessel density in HTs, while it did not affect vessel density in STs. MRI and microangiography outcomes were supported by histopathologic findings. CONCLUSIONS: MRI and microangiography allowed quantitative comparison of therapeutic responses to CA4P in rats with multifocal tumors. The discovered diverse effects of the same drug on tumors of the same origin but different locations emphasize the presence of cancer heterogeneity and the importance of individualization of drug delivery.     

High photosynthetic capacity of Sahelian C3 and C4 plants

Photosynthesis Research - The semi-arid ecosystems of the African Sahel play an important role in the global carbon cycle and are among the most sensitive ecosystems to future environmental...     

DNA-based species delimitation in algae

Given the problems of species delimitation in algae using morphology or sexual compatibility, molecular data are becoming the standard for delimiting species and testing their traditional boundaries. The idea that species are separately evolving metapopulation lineages, along with theoretical progress in phylogenetic and population genetic analyses, has led to the development of new methods of species delimitation. We review these recent developments in DNA-based species delimitation methods, and discuss how they have changed and continue to change our understanding of algal species boundaries. Although single-locus approaches have proven effective for a first rapid and large-scale assessment of species diversity, species delimitation based on single gene trees falls short due to gene tree–species tree incongruence, caused by confounding processes like incomplete lineage sorting, trans-species polymorphism, hybridization and introgression. Data from unlinked loci and multi-species coalescent methods, which combine principles from phylogenetics and population genetics, may now be able to account for these complicating factors. Several of these methods also provide statistical support regarding species boundaries, which is important because speciation is a process and therefore uncertainty about precise species boundaries is inevitable in recently diverged lineages.     

Data mining approach identifies research priorities and data requirements for resolving the red algal tree of life

Background  

The assembly of the tree of life has seen significant progress in recent years but algae and protists have been largely overlooked in this effort. Many groups of algae and protists have ancient roots and it is unclear how much data will be required to resolve their phylogenetic relationships for incorporation in the tree of life. The red algae, a group of primary photosynthetic eukaryotes of more than a billion years old, provide the earliest fossil evidence for eukaryotic multicellularity and sexual reproduction. Despite this evolutionary significance, their phylogenetic relationships are understudied. This study aims to infer a comprehensive red algal tree of life at the family level from a supermatrix containing data mined from GenBank. We aim to locate remaining regions of low support in the topology, evaluate their causes and estimate the amount of data required to resolve them.     

Multiple techniques point to oxygenic phototrophs dominating the Isopora palifera skeletal microbiome

Coral Reefs - The limestone skeleton of Scleractinian corals is a complex and intricate environment consisting of an array of ecological microniches, which harbour a vast microbial community. In...     

Synthesis and biological evaluation of 68Ga labeled bis-DOTA-3,3′-(benzylidene)-bis-(1H-indole-2-carbohydrazide) as a PET tracer for in vivo visualization of necrosis

The aim of the present study was to develop a ⁶⁸Ga labeled bis-DOTA derivative of benzylidene-bis-indole and compare the in vivo stability and biodistribution with that of the previously reported bis-DTPA derivate for in vivo imaging of necrosis using PET. Uptake of the tracer was evaluated in a mouse model of Fas-mediated hepatic apoptosis in correlation with histochemical stainings. The novel ⁶⁸Ga labeled tracer showed an improved in vivo stability and could therefore be used for selective non-invasive imaging of necrotic cell death using PET.     

Variation in HMA4 gene copy number and expression among Noccaea caerulescens populations presenting different levels of Cd tolerance and accumulation

There is huge variability among populations of the hyperaccumulator Noccaea caerulescens (formerly Thlaspi caerulescens) in their capacity to tolerate and accumulate cadmium. To gain new insights into the mechanisms underlying this variability, we estimated cadmium fluxes and further characterized the N. caerulescens heavy metal ATPase 4 (NcHMA4) gene in three populations (two calamine, Saint-Félix-de-Pallières, France and Prayon, Belgium; one serpentine, Puente Basadre, Spain) presenting contrasting levels of tolerance and accumulation. Cadmium uptake and translocation varied among populations in the same way as accumulation; the population with the highest cadmium concentration in shoots (Saint Félix-de-Pallières) presented the highest capacity for uptake and translocation. We demonstrated that the four NcHMA4 copies identified in a previous study are not fixed at the species level, and that the copy truncated in the C-terminal part encodes a functional protein. NcHMA4 expression and gene copy number was lower in the serpentine population, which was the least efficient in cadmium translocation compared to the calamine populations. NcHMA4 expression was associated with the vascular tissue in all organs, with a maximum at the crown. Overall, our results indicate that differences in cadmium translocation ability of the studied populations appear to be controlled, at least partially, by NcHMA4, while the overexpression of NcHMA4 in the two calamine populations may result from convergent evolution.