Subject:
All Disciplines Arts & Humanities Biology & Life Sciences Business & Economics Chemistry & Materials Science Computer Science & Mathematics Engineering Environmental & Earth Sciences Medicine & Pharmacology Physical Sciences Public Health & Healthcare Social Sciences
Sort:
Hottest Latest Alphabetical (A-Z) Alphabetical (Z-A)
Type:
All Topic Review Biography
Topic Review
Zinc in Modern and Fossil Hominoid Teeth
Teeth begin to grow in the jaws before birth and continue to appear in an overlapping sequence until each is complete in length. Subsequently, the central pulp (nerve) chamber of each tooth slowly fills in with dentine and the root of the tooth continues to accumulate thin layers of cementum until the individual dies. Each of the tooth tissues, the hard enamel cap, the dentine core of the tooth and the root cementum grow incrementally and incorporate small quantities of blood-born trace elements ingested from our diet into their structure. A chronological record of zinc incorporation exists in each tooth tissue and can be visualised in thin sections, or slices, of teeth using a beam of synchrotron light. Zinc markings in teeth are especially useful and occur at birth in enamel and dentine and annually in the cementum layers. This work shows that zinc is consistently concentrated within surface enamel and in the dentine surrounding the central pulp chamber. Knowing where to sample Zn in modern and fossil teeth enables us to reconstruct a chronology of growth and to determine something about diet in the past from the remnants of different Zn isotopes contained in different foodstuffs.
  • 147
  • 12 Dec 2023
Topic Review
Y Chromosome Evolution and Functional Specialization
The Y chromosome is one of the sex chromosomes found in males of animals of different taxa, including insects and mammals. Among all chromosomes, the Y chromosome is characterized by a unique chromatin landscape undergoing dynamic evolutionary change. Being entirely heterochromatic, the Y chromosome as a rule preserves few functional genes, but is enriched in tandem repeats and transposons. Due to difficulties in the assembly of the highly repetitive Y chromosome sequence, deep analyses of Y chromosome evolution, structure, and functions are limited to a few species, one of them being Drosophila melanogaster. Here researchers survey comparative evolutionary history of the fly and human Y chromosomes, and functions of Y-linked piRNA clusters ensuring sex-specific piRNA silencing. 
  • 1.1K
  • 09 May 2022
Topic Review
Volvocine regA Gene Model for Cellular Differentiation Evolution
A group of green algae in the order of Volvocales provides an ideal model system for studying the transition from unicellular to differentiated multicellularity. This group—known as the volvocine algae—evolved multicellularity relatively recently (~240 million years ago) and contains extant relatives that span a range of complexities from unicellularity, to undifferentiated multicellularity, to differentiated multicellularity. The regA-like gene family within the volvocine algae serves as a model for the evolution of the genetic basis of cellular differentiation.
  • 237
  • 04 May 2023
Topic Review
Vitamin D Scarcity in Arctic and  Tropical Peoples
Vitamin D metabolism differs among human populations because the species has adapted to different natural and cultural environments. Two environments are particularly difficult for the production of vitamin D by the skin: the Arctic, where the skin receives little solar UVB over the year; and the Tropics, where the skin is highly melanized and blocks UVB. In both cases, natural selection has favored the survival of those individuals who use vitamin D more efficiently or have some kind of workaround that ensures sufficient uptake of calcium and other essential minerals from food passing through the intestines. Vitamin D scarcity has either cultural or genetic solutions. Cultural solutions include consumption of meat in a raw or boiled state and extended breastfeeding of children. Genetic solutions include higher uptake of calcium from the intestines, higher rate of conversion of vitamin D to its most active form, stronger binding of vitamin D to carrier proteins in the bloodstream, and greater use of alternative metabolic pathways for calcium uptake. Because their bodies use vitamin D more sparingly, indigenous Arctic and Tropical peoples can be misdiagnosed with vitamin D deficiency and wrongly prescribed dietary supplements that may push their vitamin D level over the threshold of toxicity.
  • 1.1K
  • 20 Oct 2022
Topic Review
Virtual Anthropology and Paleoneurology
Advances in neuroscience have made it possible to obtain increasing information on the anatomy of the brain, at ever-higher resolutions, with different imaging techniques, on ever-larger samples. At the same time, paleoanthropology has to deal with partial reflections on the shape of the brain, on fragmentary specimens and small samples in an attempt to approach the morphology of the brain of past human species. Paleoanthropology has much to gain from interacting more with the field of neuroimaging. Improving our understanding of the morphology of the endocast necessarily involves studying the external surface of the brain and the link it maintains with the internal surface of the skull. The contribution of neuroimaging will allow us to better define the relationship between brain and endocast. Models of intra- and inter-species variability in brain morphology inferred from large neuroimaging databases will help make the most of the rare endocasts of extinct species. Moreover, exchanges between these two disciplines will also be beneficial to our knowledge of the Homo sapiens brain. Documenting the anatomy among other human species and including the variation over time within our own species are approaches that offer us a new perspective through which to appreciate what really characterizes the brain of humanity today. 
  • 576
  • 09 Nov 2021
Topic Review
Transposable Elements in Land Plants
Transposable elements (TEs) are important components of most plant genomes. These mobile repetitive sequences are highly diverse in terms of abundance, structure, transposition mechanisms, activity and insertion specificities across plant species.
  • 748
  • 06 Apr 2022
Topic Review
Transposable Elements during Sex Chromosome Differentiation
Transposable elements (TEs) comprise a substantial portion of eukaryotic genomes. They have the unique ability to integrate into new locations and serve as the main source of genomic novelties by mediating chromosomal rearrangements and regulating portions of functional genes. Recent studies have revealed that TEs are abundant in sex chromosomes.
  • 397
  • 23 May 2022
Topic Review
Transgenderizations of the Collective Psyche of Humanity
The evolving collective psyche of humanity reveals a shift from predominantly masculine to increasingly feminine characteristics since around 1500 A.D. This transformation, termed 'transgenderization,' is attributed to identified psychological factors. Remarkably, the collective psyche has undergone similar transitions in the past since the emergence of humanity.
  • 102
  • 21 Feb 2024
Topic Review
The Syngameon Enigma
When a group of three or more species are connected by hybridization, they form a syngameon.
  • 924
  • 20 Apr 2022
Topic Review
The Role of Commensal and other Non-Pathogenic Bacteria
Not only pathogenic bacteria are reservoirs of antibiotic resistance and virulence genes. Opportunistic pathogenic bacteria, commensal bacteria, and mutualistic bacteria (here named non-pathogenic for simplification) may also carry resistance and virulence genes. However, contrary to pathogenic strains, which are the target of the immune system, non-pathogenic bacteria can colonize hosts for prolonged periods because hosts do not need to be rid of them. Thus, the basic reproductive number of a non-pathogenic bacterial strain, a measure of the strain’s fitness and denoted as R0, is likely to be much higher than one. That is, the expected number of colonized hosts by a single colonized host in a population not yet colonized by that strain is higher than one, which implies that this strain can spread exponentially among hosts. This spread has peculiar consequences for the spread of virulence and resistance genes. For example, computer models that simulate the spread of these genes have shown that their diversities should correlate positively throughout microbiomes. Bioinformatics analysis with real data corroborates this expectation.
  • 730
  • 07 Feb 2023
  • Page
  • of
  • 7
Featured Entry Collections
>>

Featured Books

>>
Encyclopedia of Social Sciences
Encyclopedia of COVID-19
Encyclopedia of Fungi
Encyclopedia of Digital Society, Industry 5.0 and Smart City
Feedback