Coccolithophore biomineralization: New questions, new answers.

Coccolithophores are unicellular phytoplankton that are characterized by the presence intricately formed calcite scales (coccoliths) on their surfaces. In most cases coccolith formation is an entirely intracellular process - crystal growth is confined within a Golgi-derived vesicle. A wide range of coccolith morphologies can be found amongst the different coccolithophore groups. This review discusses the cellular factors that regulate coccolith production, from the roles of organic components, endomembrane organization and cytoskeleton to the mechanisms of delivery of substrates to the calcifying compartment. New findings are also providing important information on how the delivery of substrates to the calcification site is co-ordinated with the removal of H(+) that are a bi-product of the calcification reaction. While there appear to be a number of species-specific features of the structural and biochemical components underlying coccolith formation, the fluxes of Ca(2+) and a HCO3(-) required to support coccolith formation appear to involve spatially organized recruitment of conserved transport processes.

Coccolithophore biomineralization: New questions, new answers.

Coccolithophores are unicellular phytoplankton that are characterized by the presence intricately formed calcite scales (coccoliths) on their surfaces. In most cases coccolith formation is an entirely intracellular process - crystal growth is confined within a Golgi-derived vesicle. A wide range of coccolith morphologies can be found amongst the different coccolithophore groups. This review discusses the cellular factors that regulate coccolith production, from the roles of organic components, endomembrane organization and cytoskeleton to the mechanisms of delivery of substrates to the calcifying compartment. New findings are also providing important information on how the delivery of substrates to the calcification site is co-ordinated with the removal of H(+) that are a bi-product of the calcification reaction. While there appear to be a number of species-specific features of the structural and biochemical components underlying coccolith formation, the fluxes of Ca(2+) and a HCO3(-) required to support coccolith formation appear to involve spatially organized recruitment of conserved transport processes.

Haptophyta

Haptophyta are predominantly planktonic and phototrophic organisms that have their main distribution in marine environments worldwide. They are a major component of the microbial ecosystem, some form massive blooms and some are toxic. Haptophytes are significant players in the global carbonate cycle through photosynthesis and calcification. They are characterized by the haptonema, a third appendage used for attachment and food handling, two similar flagella, two golden-brown chloroplasts, and organic body scales that serve in species identification. Coccolithophores have calcified scales termed coccoliths. Phylogenetically Haptophyta form a well-defined group and are divided into two classes Pavlovophyceae and Coccolithophyceae (Prymnesiophyceae). Currently, about 330 species are described. Environmental DNA sequencing shows high haptophyte diversity in the marine pico- and nanoplankton, of which many likely represent novel species and lineages. Haptophyte diversity is believed to have peaked in the past and their presence is documented in the fossil record back to the Triassic, approximately 225 million years ago. Some biomolecules of haptophyte origin are extraordinarily resistant to decay and are thus used by geologists as sedimentary proxies of past climatic conditions.

Haptophyta

Haptophyta are predominantly planktonic and phototrophic organisms that have their main distribution in marine environments worldwide. They are a major component of the microbial ecosystem, some form massive blooms and some are toxic. Haptophytes are significant players in the global carbonate cycle through photosynthesis and calcification. They are characterized by the haptonema, a third appendage used for attachment and food handling, two similar flagella, two golden-brown chloroplasts, and organic body scales that serve in species identification. Coccolithophores have calcified scales termed coccoliths. Phylogenetically Haptophyta form a well-defined group and are divided into two classes Pavlovophyceae and Coccolithophyceae (Prymnesiophyceae). Currently, about 330 species are described. Environmental DNA sequencing shows high haptophyte diversity in the marine pico- and nanoplankton, of which many likely represent novel species and lineages. Haptophyte diversity is believed to have peaked in the past and their presence is documented in the fossil record back to the Triassic, approximately 225 million years ago. Some biomolecules of haptophyte origin are extraordinarily resistant to decay and are thus used by geologists as sedimentary proxies of past climatic conditions.

Why marine phytoplankton calcify

Calcifying marine phytoplankton - coccolithophores - are some of the most successful yet enigmatic organisms in the ocean, and are at risk from global change. In order to better understand how they will be affected we need to know 'why' coccolithophores calcify. Here we review coccolithophorid evolutionary history, cell biology, and insights from recent experiments to provide a critical assessment of the costs and benefits of calcification. We conclude that calcification has high energy demands, and that coccolithophores might have calcified initially to reduce grazing pressure, but that additional benefits such as protection from photo-damage and viral-bacterial attack further explain their high diversity and broad spectrum ecology. The cost-versus-benefit of these traits is illustrated by novel ecosystem modeling, although conclusive observations are still limited. In the future ocean, the trade-off between changing ecological and physiological costs of calcification and their benefits will ultimately decide how this important group is affected by ocean acidification and global warming.

Why marine phytoplankton calcify

Calcifying marine phytoplankton - coccolithophores - are some of the most successful yet enigmatic organisms in the ocean, and are at risk from global change. In order to better understand how they will be affected we need to know 'why' coccolithophores calcify. Here we review coccolithophorid evolutionary history, cell biology, and insights from recent experiments to provide a critical assessment of the costs and benefits of calcification. We conclude that calcification has high energy demands, and that coccolithophores might have calcified initially to reduce grazing pressure, but that additional benefits such as protection from photo-damage and viral-bacterial attack further explain their high diversity and broad spectrum ecology. The cost-versus-benefit of these traits is illustrated by novel ecosystem modeling, although conclusive observations are still limited. In the future ocean, the trade-off between changing ecological and physiological costs of calcification and their benefits will ultimately decide how this important group is affected by ocean acidification and global warming.

Environmental carbonate chemistry selects for phenotype of recently isolated strains of Emiliania huxleyi

Coccolithophorid algae, particularly Emiliania huxleyi, are prolific biomineralisers that, under many conditions, dominate communities of marine eukaryotic plankton. Their ability to photosynthesise and form calcified scales (coccoliths) has placed them in a unique position in the global carbon cycle. Contrasting reports have been made with regards to the response of E. huxleyi to ocean acidification. Therefore, there is a pressing need to further determine the fate of this key organism in a rising CO2 world. In this paper, we investigate the phenotype of newly isolated, genetically diverse, strains of E. huxleyi from UK Ocean Acidification Research Programme (UKOA) cruises around the British Isles, the Arctic, and the Southern Ocean. We find a continuum of diversity amongst the physiological and photosynthetic parameters of different strains of E. huxleyi morphotype A under uniform, ambient conditions imposed in the laboratory. This physiology is best explained by adaptation to carbonate chemistry in the former habitat rather than being prescribed by genetic fingerprints such as the coccolithophore morphology motif (CMM). To a first order, the photosynthetic capacity of each strain is a function of both aqueous CO2 availability, and calcification rate, suggestive of a link between carbon concentrating ability and calcification. The calcification rate of each strain is related linearly to the natural environmental [CO32−] at the site of isolation, but a few exceptional strains display low calcification rates at the highest [CO32−] when calcification is limited by low CO2 availability and/or a lack of a carbon concentrating mechanism. We present O2-electrode measurements alongside coccolith oxygen isotopic composition and the uronic acid content (UAC) of the coccolith associated polysaccharide (CAP), that act as indirect tools to show the differing carbon concentrating ability of the strains. The environmental selection revealed amongst our recently isolated strain collection points to the future outcompetition of the slow growing morphotypes B/C and R (which also lack a carbon concentrating mechanism) by more rapidly photosynthesising, and lightly calcified strains of morphotype A but with their rate of calcification highly dependent on the surface ocean saturation state. The mechanism of E. huxleyi response to carbonate chemistry in the modern ocean appears to be selection from a continuum of phenotype.

Environmental carbonate chemistry selects for phenotype of recently isolated strains of Emiliania huxleyi

Coccolithophorid algae, particularly Emiliania huxleyi, are prolific biomineralisers that, under many conditions, dominate communities of marine eukaryotic plankton. Their ability to photosynthesise and form calcified scales (coccoliths) has placed them in a unique position in the global carbon cycle. Contrasting reports have been made with regards to the response of E. huxleyi to ocean acidification. Therefore, there is a pressing need to further determine the fate of this key organism in a rising CO2 world. In this paper, we investigate the phenotype of newly isolated, genetically diverse, strains of E. huxleyi from UK Ocean Acidification Research Programme (UKOA) cruises around the British Isles, the Arctic, and the Southern Ocean. We find a continuum of diversity amongst the physiological and photosynthetic parameters of different strains of E. huxleyi morphotype A under uniform, ambient conditions imposed in the laboratory. This physiology is best explained by adaptation to carbonate chemistry in the former habitat rather than being prescribed by genetic fingerprints such as the coccolithophore morphology motif (CMM). To a first order, the photosynthetic capacity of each strain is a function of both aqueous CO2 availability, and calcification rate, suggestive of a link between carbon concentrating ability and calcification. The calcification rate of each strain is related linearly to the natural environmental [CO32−] at the site of isolation, but a few exceptional strains display low calcification rates at the highest [CO32−] when calcification is limited by low CO2 availability and/or a lack of a carbon concentrating mechanism. We present O2-electrode measurements alongside coccolith oxygen isotopic composition and the uronic acid content (UAC) of the coccolith associated polysaccharide (CAP), that act as indirect tools to show the differing carbon concentrating ability of the strains. The environmental selection revealed amongst our recently isolated strain collection points to the future outcompetition of the slow growing morphotypes B/C and R (which also lack a carbon concentrating mechanism) by more rapidly photosynthesising, and lightly calcified strains of morphotype A but with their rate of calcification highly dependent on the surface ocean saturation state. The mechanism of E. huxleyi response to carbonate chemistry in the modern ocean appears to be selection from a continuum of phenotype.

Effet des différents apports alimentaires de phosphore et de calcium sur les performances de croissance, la minéralisation osseuse et l’ostéochondrose chez le porc

L’objectif principal de ce mémoire était de déterminer les apports optimaux en phosphore (P) en termes de performance de croissance, de minéralisation osseuse, d’excrétion de P et de fréquence d’ostéochondrose chez le porc (25 à 120 kg). L’expérience s’est échelonnée sur trois phases de 28 jours chacune où les porcs ont été alimentés avec des nourrisseurs automatiques. Deux aliments, soit un riche en nutriments (A) qui satisfait les besoins d’un porc de 25 kg en plus d’apporter 140 % des besoins en P digestible et en calcium (Ca) et un autre pauvre en nutriments (B) satisfaisant les besoins d’un porc de 120 kg en plus d’apporter 60 % des besoins en P digestible et en Ca ont été utilisés pour fabriquer 5 des traitements alimentaires, et le 6e traitement constituait le témoin positif. Pendant la première phase, 80 porcs ont reçu un des 5 traitements alimentaires, soit 60, 80, 100, 120 et 140 % des besoins en P avec un rapport Ca :P fixe. De faibles différences au niveau des performances de croissance ont été observées entre les traitements. La minéralisation osseuse a pour sa part augmenté linéairement avec l’augmentation des apports phosphocalciques. Aux phases 2 et 3, une erreur expérimentale s’est glissée dans la composition des aliments A et B, faisant en sorte que les quantités de Ca de chacun des deux aliments ont été inversées, soit des apports de P toujours de 60, 80, 100, 120 et 140 % des besoins, mais conjointement avec des apports de Ca de 140, 115, 100, 85 et 70 % des besoins respectivement. Ainsi, l’objectif de l’essai a été revu en tenant compte de cette erreur pour étudier l’effet de déséquilibres phosphocalciques sur les mêmes critères que ceux de la phase 1. Les résultats montrent l’importance de maintenir un équilibre entre les apports de P et de Ca afin de favoriser l’utilisation de chacun des deux éléments.

Effects of ocean acidification on embryo development: Does encapsulation matter?

As the concentration of CO2 in surface seawaters increases (ocean acidification, or OA) the saturation of calcium carbonate decreases, preventing marine organisms from creating shells and other calcified structures. These effects of elevated CO2 on calcification have been previously shown in free-spawning larvae, but are not as well-studied in larvae that spend their early life stages in encapsulation. The focus of our study was to determine what effects CO2 would have on a diversity of encapsulated embryos, and whether different types of encapsulating structures provided different levels of protection against OA. We found only a moderate larval response to low (600 ppm), medium (1050 ppm), and high (1500 ppm) CO2 concentrations across all species taken as a whole, but did observe that several species/ populations exhibited a decline in shell length with no corresponding decline in inorganic content. This suggests that while calcification was not significantly decreased by our OA conditions, perhaps the morphology of certain shells changed, becoming wider and shorter. Our hatch times, which increased with elevated CO2, confirmed that increased CO2 placed embryos under stress during development.

Squamous cell carcinoma of the renal pelvis with stones and inferior vena cava infiltration. Case report

We report a rare case of a 50 year old man with renal squamous cell carcinoma (SCC) who first came to our attention with renal colic and fever not responding to antibiotic or analgesic treatment. He had a long history of kidney stones, but had not undergone any imaging in the last 5 years. Physical examination revealed tenderness and a palpable mass in the right flank and lumbar region. A whole body CT scan was performed, revealing an 11 cm mass in the right kidney infiltrating the inferior vena cava. There were areas of calcification within the mass and multiple stones within the renal pelvis. The tumor was considered unsuitable for resection according to radiological and clinical criteria. The mass was biopsied percutaneously under CT guidance and histological examination revealed squamous cell carcinoma of the renal pelvis. The patient was treated with neoadjuvant chemotherapy and embolization of the renal artery. He died one month after diagnosis. To our knowledge this is the second reported case in the world of renal SCC infiltrating the inferior vena cava and with kidney stones.

Canais calcificados

A abordagem Endodôntica tem como grandes objetivos a manutenção funcional e estética do dente no sistema estomatognático. O sucesso desta abordagem terapêutica depende da realização eficiente da desinfeção, conformação e obturação do canal radicular. Estas etapas podem tornar-se difíceis de realizar na presença de dentes calcificados. A localização e manipulação dos canais calcificados são considerados um grande desafio durante a abordagem Endodôntica. Na tentativa de localização dos canais podem ocorrer erros de procedimento, como perfurações, fraturas de instrumentos e desvios do trajeto original do canal. Atualmente, vários recursos clínicos são utilizados para auxiliar estes procedimentos, como radiografias, microscópio operatório e o ultrassom. A calcificação pode ser resultado do processo fisiológico de envelhecimento, ou da deposição de dentina como mecanismo de defesa da polpa contra agentes agressores externos. Os dentes com calcificação não costumam apresentar sintomatologia, sendo o diagnóstico muitas vezes acidental. Clinicamente, a coroa dentária apresenta coloração alterada, e radiograficamente os canais apresentam os seus limites pulpares apagados, revelando obstrução parcial ou completa da câmara pulpar e dos canais, devido à deposição excessiva de dentina. A abordagem apropriada para dentes calcificados pode ser um dilema para o clínico. Esta deve ser feita a partir de decisão prudente entre a intervenção Endodôntica para o dente envolvido e outras intervenções restauradoras estéticas disponíveis. A maioria da literatura não apoia a intervenção Endodôntica a menos que seja detetado patologia apical ou sintomatologia do dente envolvido. A observação e o exame periódico do dente calcificado são as opções geralmente adotadas.

The Phosphate Source Influences Gene Expression and Quality of Mineralization during In Vitro Osteogenic Differentiation of Human Mesenchymal Stem Cells

For in vitro differentiation of bone marrow-derived mesenchymal stem cells/mesenchymal stromal cells into osteoblasts by 2-dimensional cell culture a variety of protocols have been used and evaluated in the past. Especially the external phosphate source used to induce mineralization varies considerably both in respect to chemical composition and concentration. In light of the recent findings that inorganic phosphate directs gene expression of genes crucial for bone development, the need for a standardized phosphate source in in vitro differentiation becomes apparent. We show that chemical composition (inorganic versus organic phosphate origin) and concentration of phosphate supplementation exert a severe impact on the results of gene expression for the genes commonly used as markers for osteoblast formation as well as on the composition of the mineral formed. Specifically, the intensity of gene expression does not necessarily correlate with a high quality mineralized matrix. Our study demonstrates advantages of using inorganic phosphate instead of beta-glycerophosphate and propose colorimetric quantification methods for calcium and phosphate ions as cost-and time-effective alternatives to X-ray diffraction and Fourier-transform infrared spectroscopy for determination of the calcium phosphate ratio and concentration of mineral matrix formed under in vitro-conditions. We critically discuss the different assays used to assess in vitro bone formation in respect to specificity and provide a detailed in vitro protocol that could help to avoid contradictory results due to variances in experimental design.