Mineral skeletogenesis in sponges

2006 ◽  
Vol 84 (2) ◽  
pp. 322-356 ◽  
Author(s):  
María-J. Uriz
Keyword(s):  
Organic Molecules ◽  
Current Knowledge ◽  
Axial Filament ◽  
Environment Variables ◽  
Siliceous Sponges ◽  
Predominant Process ◽  
Points Of View ◽  
Siliceous Spicules ◽  
Genetically Determined ◽  
Axes Of Symmetry

Sponges secrete a variety of mineral skeletons consisting of calcite, aragonite, and (or) amorphous silica that confer strength and protect them from physical perturbations. Calcification takes place in a solution of bicarbonate and calcium ions, which is supersaturated with respect to both calcite and aragonite. In contrast, siliceous spicules are formed from an environment that is undersaturated with respect to silicon. Silification is the predominant process of biomineralization in extant sponges (92% of the species). The number of axes of symmetry in the large skeletal elements (megasclere spicules) is the main skeletal difference between the classes Hexactinellida (monaxons and triaxons) and Demospongiae (monaxons and tetraxons). Hypersilification occurs in both lithistid demosponges and hexactinellids, which are mostly confined to silicon-rich environments. Both siliceous and calcareous sponge skeletons are deposited within a well-defined restricted space by the so-called matrix-mediated mineralization. Both processes require organic molecules, which are secreted by a particular cell type (sclerocytes) and guide spicule formation. In most siliceous sponges, these molecules form a discrete filament, which is mainly triangular or quadrangular in cross section in demosponges and hexactinellids, respectively. No discrete axial filament has been reported for calcareous sponges. Silica polycondensation produces nanospheres to microspheres, which are arranged in concentric layers to form the spicules. The potential number of siliceous spicule types in a sponge species appears to be fixed genetically, but the environmental conditions (specifically the availability of silicon) may determine whether a genetically determined spicule type is finally expressed. In this study I review the current knowledge on sponge skeletogenesis, from molecular, cellular, and structural points of view. The contribution of environment variables, as well as the proliferation and decay of the main skeleton types in the past, are also considered.

scholarly journals Potential predictors of severe cardiovascular involvement in Marfan syndrome: the emphasized role of genotype–phenotype correlations in improving risk stratification—a literature review

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Roland Stengl ◽  
Bence Ágg ◽  
Miklós Pólos ◽  
Gábor Mátyás ◽  
Gábor Szabó ◽  
...  
Keyword(s):  
Risk Stratification ◽  
Marfan Syndrome ◽  
Current Knowledge ◽  
Imaging Techniques ◽  
Connective Tissue Disorder ◽  
Main Body ◽  
Wide Range ◽  
Stratification System ◽  
Genetically Determined ◽  
Aortic Dissections

Abstract Background Marfan syndrome (MFS) is a genetically determined systemic connective tissue disorder, caused by a mutation in the FBN1 gene. In MFS mainly the cardiovascular, musculoskeletal and ocular systems are affected. The most dangerous manifestation of MFS is aortic dissection, which needs to be prevented by a prophylactic aortic root replacement. Main body The indication criteria for the prophylactic procedure is currently based on aortic diameter, however aortic dissections below the threshold defined in the guidelines have been reported, highlighting the need for a more accurate risk stratification system to predict the occurrence of aortic complications. The aim of this review is to present the current knowledge on the possible predictors of severe cardiovascular manifestations in MFS patients, demonstrating the wide range of molecular and radiological differences between people with MFS and healthy individuals, and more importantly between MFS patients with and without advanced aortic manifestations. These differences originating from the underlying common molecular pathological processes can be assessed by laboratory (e.g. genetic testing) and imaging techniques to serve as biomarkers of severe aortic involvement. In this review we paid special attention to the rapidly expanding field of genotype–phenotype correlations for aortic features as by collecting and presenting the ever growing number of correlations, future perspectives for risk stratification can be outlined. Conclusions Data on promising biomarkers of severe aortic complications of MFS have been accumulating steadily. However, more unifying studies are required to further evaluate the applicability of the discussed predictors with the aim of improving the risk stratification and therefore the life expectancy and quality of life of MFS patients.

The champions' mitochondria: is it genetically determined? A review on mitochondrial DNA and elite athletic performance

2011 ◽  
Vol 43 (13) ◽  
pp. 789-798 ◽  
Author(s):  
Nir Eynon ◽  
María Morán ◽  
Ruth Birk ◽  
Alejandro Lucia
Keyword(s):  
Mitochondrial Dna ◽  
Endurance Exercise ◽  
Current Knowledge ◽  
Geographic Origin ◽  
Aerobic Performance ◽  
East African ◽  
Athletic Status ◽  
The Status ◽  
Genetically Determined ◽  
Mtdna Variants

Aerobic ATP generation by the mitochondrial respiratory oxidative phosphorylation system (OXPHOS) is a vital metabolic process for endurance exercise. Notably, mitochondrial DNA (mtDNA) codifies 13 of the 83 polypeptides implied in the respiratory chain. As such, there is a strong rationale for identifying an association between mtDNA variants and “aerobic” (endurance) exercise phenotypes. The aim of this review is to summarize current knowledge on the association between mtDNA, nuclear genes involved in mitochondriogenesis, and elite endurance athletic status. Several studies in nonathletic people have demonstrated an association between certain mtDNA lineages and aerobic performance, characterized by maximal oxygen uptake (V̇o2max). Whether mtDNA haplogroups are also associated with the status of being an elite endurance athlete is more controversial, with differences between studies arising from the different ethnic backgrounds of the athletic cohorts (Caucasian of mixed geographic origin, Asiatic, or East African).

scholarly journals Um altar funerário romano em Bustelo (Penafiel, Porto, Norte de Portugal)

2021 ◽  
Vol 42 ◽  
pp. 85-109
Author(s):  
Teresa Soeiro ◽  
Armando Redentor
Keyword(s):  
Current Knowledge ◽  
Points Of View

This paper presents the study of an inscribed Roman funerary altar, found in 2020 in the old monastery of Bustelo (Penafiel). The circumstances of the finding were recorded as well as the possible post-Roman era route of the piece and its reuse. The study of the typological characteristics of the support is carried out and the text is analysed from the epigraphic and historical points of view, seeking to contextualize the monument in the regional epigraphy. Taking into account the current knowledge about Roman sites in the vicinity of the finding place, the potential connexion with contemporary settlements of the altar making and primary use is discussed.

scholarly journals Photoinduced C–H bond fission in prototypical organic molecules and radicals

2019 ◽  
Vol 21 (26) ◽  
pp. 13880-13901 ◽  
Author(s):  
Michael N. R. Ashfold ◽  
Rebecca A. Ingle ◽  
Tolga N. V. Karsili ◽  
Jingsong Zhang
Keyword(s):  
Organic Molecules ◽  
Current Knowledge ◽  
Primary Photochemistry ◽  
Hydrocarbon Molecules

We survey and assess current knowledge regarding the primary photochemistry of hydrocarbon molecules and radicals.

SCREENING EFFECTS AT ORGANIC–2D MATERIAL HETEROINTERFACES

2021 ◽  
pp. 2140008
Author(s):  
YU JIE ZHENG ◽  
ARRAMEL
Keyword(s):  
Organic Molecules ◽  
Current Knowledge ◽  
Raw Materials ◽  
2D Materials ◽  
Absorption Efficiency ◽  
Material Interfaces ◽  
Material Interface ◽  
Screening Effect ◽  
2D Material ◽  
Dielectric Screening

Organic molecule–two-dimensional material (OM–2D material) heterostructures are relatively an emergent class of hybrid-based electronic devices and yet have gained enormous interests. These systems hold promise towards application in the realization of electronic, optoelectronic and energy conversion devices, due to their tunable thickness, rich raw materials, flexibility, and also their capability to merge the high light absorption efficiency of organic molecules and the high carrier mobility of 2D materials. Dielectric screening effects have a large influence on electronic structure and optical properties at the OM–2D material interface due to the low intrinsic dielectric polarizability of both organic molecules and 2D materials. Here, we will review current knowledge about the dielectric screening behaviors in 2D materials and the screening effect at the OM–2D material heterointerfaces, including the physical origin of the dielectric screening effect across such interfaces, how to investigate it, and the influence of the screening effect on OM–2D material interfaces. Engineering of the dielectric screening effects in OM–2D material systems is also discussed. We conclude the review by illustrating a brief introduction of other important factors, e.g. defects, charge transfer, and hybridization, that will contribute to the screening effect and these features should be considered for the future scientific and device development of OM–2D material heterostructures.

AUTOSOMAL DISORDERS

PEDIATRICS ◽  
1963 ◽  
Vol 32 (3) ◽  
pp. 326-337
Author(s):  
Jerome Lejeune
Keyword(s):  
Mental Retardation ◽  
Sex Chromosomes ◽  
Current Knowledge ◽  
Chromosome 17 ◽  
Chromosome 22 ◽  
Severe Mental Retardation ◽  
General Survey ◽  
Human Cytogenetics ◽  
Points Of View ◽  
Hands And Feet

THE RAPID GROWTH of human cytogenetics imposes, as a corollary, the progressive restriction of the scope of a talk on this subject. Two years ago, a quarter of an hour was sufficient for a general survey; today, a whole hour is filled with one topic only. Without being a prophet, it can be seriously foreseen that some day, a Blackfan Lecture restricted to "the genic content of the short arm of chromosome 22" will be considered a very brief summary of the current knowledge. I would like to discuss the general implications of the available data on autosomal disorders. Chromosomes are divided into sex chromosomes and non-sex chromosomes, which are generally called autosomes. My subject can be considered under three points of view: the recognition of autosomal disorders, the mechanism of their production and, finally, the practical or heuristic use of this knowledge, as it enables more to be learned. SYNDROMES DETERMINED BY AUTOSOMAL DISORDERS The Numerical Abnormalities The numerical abnormalities are no longer limited to classic mongolism, with its 47 chromosomes and its trisomy for No. 21.1-3 The trisomy for chromosome 17, in which there occurs a typical deformity of the head, a small mandible, low set ears, other nonspecific malformations of heart, hands and feet, and severe mental retardation, is also quite classic. Possibly more than 25 different patients suffering from this disease are now known. The 13-15 trisomy with eyeball defects, polydactyly, cardiopathy, and mental defect, together with deformities of lips, palate, skin, and ears is also well established.

Effect of Vulcanization on Rubber Structure. A Problem in Probabilities

1940 ◽  
Vol 13 (2) ◽  
pp. 196-208
Author(s):  
Warren F. Busse
Keyword(s):  
Chemical Analysis ◽  
Physical Properties ◽  
Organic Molecules ◽  
Cold Winter ◽  
Winter Weather ◽  
The Past ◽  
Points Of View ◽  
Physical And Chemical ◽  
Present View

Abstract In Goodyear's day, the problem of understanding the process of vulcanization could be expressed by the question: “Why does heating rubber with sulfur keep it from getting soft and tacky on a hot summer day, and hard and boardy in cold winter weather?” The deceptive simplicity of this question probably inspired the hope, which has come down almost to the present day, that the secrets of vulcanization and even of the elasticity of rubber could be explained in terms of the properties and reactions of simple organic molecules, such as the reactions of sulfur with simple olefins. The vast increase in the knowledge of giant molecules during the past decade has shattered any basis there may have been for such a hope, but occasional articles show that this desire for simplicity continues to live and to color our thinking on this problem. This paper discusses some of the inherent limitations of the old, simpler pictures of vulcanization and the structure of rubber, and some of the implications of the present view that crude rubber is built up of giant molecules. Probably there are not merely one or two or half a dozen reactions, but rather there are literally millions of possible vulcanization reactions, each of which may influence the physical properties of the rubber. The study of these reactions will require new and far more sensitive methods of physical and chemical analysis than have been available heretofore, as well as new points of view in interpreting the data.

scholarly journals Genetic susceptibility to type 1 diabetes mellitus in humans

2007 ◽  
pp. 255-266
Author(s):  
D Kantárová ◽  
M Buc
Keyword(s):  
Diabetes Mellitus ◽  
Type 1 Diabetes ◽  
Type 1 Diabetes Mellitus ◽  
Current Knowledge ◽  
Insulin Dependent Diabetes Mellitus ◽  
Dependent Diabetes Mellitus ◽  
Immune Mediated ◽  
Insulin Dependent ◽  
Genetically Determined

Type 1 diabetes mellitus (DM 1A) is an autoimmune disease belonging to the most frequent chronic diseases of the childhood and young adults. DM 1A results from immune-mediated destruction of the insulin-producing beta cells of the pancreas. It is a genetically determined disease and many genes or genetic regions were found to be associated with its induction. In addition to the insulin-dependent diabetes mellitus 1 (IDDM1) gene, which marks the HLA region, and IDDM2 which marks the insulin gene, significant associations of DM 1A to other IDMM genes or genetic regions we reported. We shortly review recent achievements in the field, and the state of current knowledge.

scholarly journals Effects of Primary Mast Cell Disease on Hemostasis and Erythropoiesis

2021 ◽  
Vol 22 (16) ◽  
pp. 8960
Author(s):  
Holger Seidel ◽  
Hans-Jörg Hertfelder ◽  
Johannes Oldenburg ◽  
Johannes P. Kruppenbacher ◽  
Lawrence B. Afrin ◽  
...  
Keyword(s):  
Mast Cell ◽  
Current Knowledge ◽  
Clinical Manifestations ◽  
Disease Entity ◽  
Cell Disease ◽  
Excessive Bleeding ◽  
Mast Cell Disease ◽  
Genetically Determined ◽  
The Impact ◽  
Work Up

Mast cell disease is an epigenetically and genetically determined disease entity with very diverse clinical manifestations in potentially every system and tissue due to inap pro priate release of variable subsets of mast cell mediators together with accumulation of either morphologically normal or altered mast cells. Easy bruising, excessive bleeding, and aberrancies of erythropoiesis can frequently be observed in patients with mast cell disease. A thorough history, including a family history, will guide the appropriate work-up, and laboratory evaluations may provide clues to diagnosis. In recent years, our understanding of the involvement of coagulation and anticoagulant pathways, the fibrinolytic system, and erythropoiesis in the pathophysiology of mast cell disease has increased considerably. This review summarizes current knowledge of the impact of the disturbed hemostatic and erythropoietic balance in patients with mast cell disease and describes options of treatment.

Functional Somatic Symptoms and Somatization: Person-centered Approach to Understanding their Relationships

2019 ◽  
Vol 7 (4) ◽  
Author(s):  
Ariel Falcoff
Keyword(s):  
Somatoform Disorders ◽  
Current Knowledge ◽  
General Medicine ◽  
General Factor ◽  
Visible Points ◽  
Functional Symptoms ◽  
The Subject ◽  
Points Of View ◽  
Person Centered Approach ◽  
The Relationship

Background: Despite the visible points of overlapping between the psychopathologic concepts of "somatization" and "somatoform disorders" with those of "functional symptoms" and "somatic syndromes" of general medicine, there is little literature which clarifies their relationships, making it difficult to formulate common grounds for work between psychiatry and the rest of medicine. Objectives: The purpose of this article is to review and critically analyze current knowledge on the subject, in search for conceptual links between different paradigms involving the underlying phenomena, proposing present and future lines of work according to the basic concepts of the Person Centered Medicine. Methodology: A wide ranging review and critical analysis of the literature on these subjects was conducted, trying to explore the relationship and integration of different paradigms according to the MCP framework and an outline of the author´s current research. Results: A need was found to establish transdisciplinary concepts which leave aside the particular visions of each paradigm, in search for links which may integrate different insights, considering the person as a whole. Therefore, it is essential to analyze carefully the phenomenon from various points of view to elucidate wider conceptualizations so as to reformulate this spectrum of phenomena from an integrative perspective. The possibility of the existence of a “general factor”, both present in the so-called “functional” disorder of general medicine, and in those that in psychopathology are grouped as somatization, is suggested. This general factor could be represented by certain personality dimensions and psychic representations encompassed by complex context variables. Conclusions: It would be valuable to continue with research of this phenomena structure as well as to look for strategies to benefit from the theoretical findings in the health care field, according to the proposals of Person Centered Medicine.

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