scholarly journals Why Do Some Vertebrates Have Microchromosomes?

Cells ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2182
Author(s):  
Kornsorn Srikulnath ◽  
Syed Farhan Ahmad ◽  
Worapong Singchat ◽  
Thitipong Panthum

With more than 70,000 living species, vertebrates have a huge impact on the field of biology and research, including karyotype evolution. One prominent aspect of many vertebrate karyotypes is the enigmatic occurrence of tiny and often cytogenetically indistinguishable microchromosomes, which possess distinctive features compared to macrochromosomes. Why certain vertebrate species carry these microchromosomes in some lineages while others do not, and how they evolve remain open questions. New studies have shown that microchromosomes exhibit certain unique characteristics of genome structure and organization, such as high gene densities, low heterochromatin levels, and high rates of recombination. Our review focuses on recent concepts to expand current knowledge on the dynamic nature of karyotype evolution in vertebrates, raising important questions regarding the evolutionary origins and ramifications of microchromosomes. We introduce the basic karyotypic features to clarify the size, shape, and morphology of macro- and microchromosomes and report their distribution across different lineages. Finally, we characterize the mechanisms of different evolutionary forces underlying the origin and evolution of microchromosomes.

Author(s):  
Alfonso Troisi

From the perspective of evolutionary biology, diversity is an intrinsic feature of any living species and a target on which natural selection can act in opposite ways: either decreasing it (stabilizing selection) or increasing it (diversifying selection). This duality is reflected in our emotional attitude toward diversity. This chapter summarizes current knowledge on the evolutionary origins of emotional reactions to physical and behavioral diversity in human cultures. After a preliminary discussion of “alternative strategies” observed by ethologists in primate species, the chapter explores the biological roots of intolerance, xenophobia, racism, discrimination, and other forms of rejection of diversity. Findings that have linked ethnocentrism to primitive defenses against infectious diseases are reviewed. Subsequently, the chapter describes how a bias toward “normality” has always lived alongside a powerful attraction to diversity. The chapter closes with reflections based on recent psychiatric and anthropological reports that show how the issue of tolerance of cultural diversity is an unsolved problem, in spite of reassuring claims of the advocates of cultural relativism.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Philipp Schult ◽  
Katrin Paeschke

AbstractDHX36 is a member of the DExD/H box helicase family, which comprises a large number of proteins involved in various cellular functions. Recently, the function of DHX36 in the regulation of G-quadruplexes (G4s) was demonstrated. G4s are alternative nucleic acid structures, which influence many cellular pathways on a transcriptional and post-transcriptional level. In this review we provide an overview of the current knowledge about DHX36 structure, substrate specificity, and mechanism of action based on the available models and crystal structures. Moreover, we outline its multiple functions in cellular homeostasis, immunity, and disease. Finally, we discuss the open questions and provide potential directions for future research.


Viruses ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 504
Author(s):  
Ananda Ayyappan Jaguva Vasudevan ◽  
Daniel Becker ◽  
Tom Luedde ◽  
Holger Gohlke ◽  
Carsten Münk

Non-human primates (NHP) are an important source of viruses that can spillover to humans and, after adaptation, spread through the host population. Whereas HIV-1 and HTLV-1 emerged as retroviral pathogens in humans, a unique class of retroviruses called foamy viruses (FV) with zoonotic potential are occasionally detected in bushmeat hunters or zookeepers. Various FVs are endemic in numerous mammalian natural hosts, such as primates, felines, bovines, and equines, and other animals, but not in humans. They are apathogenic, and significant differences exist between the viral life cycles of FV and other retroviruses. Importantly, FVs replicate in the presence of many well-defined retroviral restriction factors such as TRIM5α, BST2 (Tetherin), MX2, and APOBEC3 (A3). While the interaction of A3s with HIV-1 is well studied, the escape mechanisms of FVs from restriction by A3 is much less explored. Here we review the current knowledge of FV biology, host restriction factors, and FV–host interactions with an emphasis on the consequences of FV regulatory protein Bet binding to A3s and outline crucial open questions for future studies.


Author(s):  
Attila Gere ◽  
Abdul Hannan Bin Zulkarnain ◽  
Dorina Szakál ◽  
Orsolya Fehér ◽  
Zoltán Kókai

AbstractVirtual reality (VR) offers a new instrument for food scientists to evaluate different aspects of food products. The possible applications range from product design testing, evaluation of the labels, effects of different placements or the evaluation of store layouts. These analyses help us to get a deeper understanding of consumers' minds. Additionally, VR can be coupled by several different tools (e.g. eye-trackers or skin conductance sensors or even electroencephalographs). However, as there have been only a limited number of applications published, there are several open questions which need to be answered. In the presented paper the authors aim i) to introduce the current knowledge on VR applications in food science by introducing several fields of applications and ii) to point out the most important questions regarding the applications of VR in food science.


2017 ◽  
Vol 8 (1-IT) ◽  
Author(s):  
Mario Tanga ◽  
Giacomo Gelati ◽  
Marco Casazza

6Contemporary science and culture show more and more extended and meaningful signs about the increasing explaining power of evolutionary paradigm. This power overcomes the field of the history of living species. We consider “On the Origin of Species” of 1859 by Charles Darwin as the establishment of this paradigm, but this original and fruitful idea has received the several and different contributions from near and (seemingly) far scientific fields. This process happened according distinguishable waves and leaded the evolutionary theory very far from its starting point, making it something wider and different. The current knowledge of this theory involves many kinds of scholars: biologists, zoologists, botanists, development biologists, genetics/genomics scholars and also scholars of many other disciplines, as statistics, mathematics, ecology, environmental sciences, physics, chemistry, linguistics, sociology, neuro-sciences, epidemiology, informatics, immunology. During the end of XX Century, the study of complexity, of self-organization and of emerging properties has been a decisive factor to extend evolution until beyond the boundaries of Biology. These phenomena, or properties, or features, that are shown by “living” and “not-living” systems (so called basing ourselves on traditional definitions), have deeply modified even the “properly” biologic evolution itself and besides this has demonstrated that, mutatis mutandis, evolutionary processes or phenomena happen also out of biologic dominion, referring “biologic” to “wet-ware world”. This is to say the class of evolutionary phenomena is more widely and more inclusively extended than our opinion. We can mean this as a revolution (according to Kuhn’s definition) that imposes us to restructure the definition of evolution itself and even to redraw the boundaries and the map of Biology itself. Aiming to establish a name of this field of study we propose “PanEvolutionary Theory” (PanEvo Theory). No doubt Prigogine offered an important contribution to this area. The thinking and the work of Enzo Tiezzi can be placed seen in the same perspective. Disregarding direct connections and contacts with the Nobel Prize Prigogine, however the studies of Enzo Tiezzi are neither a fully unexpected work nor a theory lacking of important potentialities: it is not a strange or eccentric academic exercise. Except the close contact and the dense exchanges with Prigogine, we collocate Enzo Tiezzi in the same context of Gregory Chaitin, of Rachel Carson, of John Harte and Robert H. Socolow, of James Paul Wesley, of Sertorio, of Oort and Peixoto, just to cite the most strictly related. Our Academy had the privilege and the honor of having Enzo Tiezzi in its ranks. We think that merits and developments of the thinking of this scholar have to produce important and lasting fruits in the future.


2021 ◽  
Author(s):  
Pavitra Ramdas ◽  
Vipin Bhardwaj ◽  
Aman Singh ◽  
Nagarjun Vijay ◽  
Ajit Chande

SERINC5 restricts nef-defective HIV-1 by affecting early steps of the virus life cycle. Distant retroviruses with a wide host-range encode virulent factors in response to the challenge by SERINC5. Yet, the evolutionary origins of this anti-retroviral activity, its prevalence among the paralogs, and its ability to target retroviruses remain understudied. In agreement with previous studies, we find that four human SERINC paralogs inhibit nef-defective HIV-1, with SERINC2 being an exception. Here, we demonstrate that this lack of activity in human SERINC2 is associated with its post-whole genome duplication (WGD) divergence, as evidenced by the ability of pre-WGD orthologs from yeast, fly, and a post-WGD-proximate SERINC2 from coelacanth to inhibit the virus. Intriguingly, Nef is unable to counter coelacanth SERINC2, indicating that such activity was directed towards other retroviruses found in coelacanth (like foamy viruses). However, foamy-derived vectors are intrinsically resistant to the action of SERINC2, and we show that the foamy virus envelope confers this resistance by affecting its steady-state levels. Our study highlights an ancient origin of anti-retroviral activity in SERINCs and a hitherto unknown interaction with a foamy virus. Importance SERINC5 constitutes a critical barrier to the propagation of retroviruses as highlighted by parallel emergence of anti-SERINC5 activities among distant retroviral lineages. Therefore, understanding the origin and evolution of these host factors will provide key information about virus-host relationships that can be exploited for future drug development. Here we show that SERINC5-mediated nef-defective HIV-1 infection inhibition is evolutionarily conserved. SERINC2 from coelacanth restricts HIV-1 and it was functionally adapted to target foamy viruses. Our findings provide insights into the evolutionary origin of anti-retroviral activity in SERINC gene family and uncover the role of SERINCs in shaping the long-term conflicts between retroviruses and their hosts.


Author(s):  
Nadège Guiglielmoni ◽  
Ramón Rivera-Vicéns ◽  
Romain Koszul ◽  
Jean-François Flot

Non-vertebrate species represent about ~95% of known metazoan (animal) diversity. They remain to this day relatively unexplored genetically, but understanding their genome structure and function is pivotal for expanding our current knowledge of evolution, ecology and biodiversity. Following the continuous improvements and decreasing costs of sequencing technologies, many genome assembly tools have been released, leading to a significant amount of genome projects being completed in recent years. In this review, we examine the current state of genome projects of non-vertebrate animal species. We present an overview of available sequencing technologies, assembly approaches, as well as pre and post-processing steps, genome assembly evaluation methods, and their application to non-vertebrate animal genomes.


Author(s):  
Jeremy M. Chacón ◽  
Sarah P. Hammarlund ◽  
Jonathan N.V. Martinson ◽  
Leno B. Smith ◽  
William R. Harcombe

Mutually beneficial interspecific interactions are abundant throughout the natural world, including between microbes. Mutualisms between microbes are critical for everything from human health to global nutrient cycling. Studying model microbial mutualisms in the laboratory enables highly controlled experiments for developing and testing evolutionary and ecological hypotheses. In this review, we begin by describing the tools available for studying model microbial mutualisms. We then outline recent insights that laboratory systems have shed on the evolutionary origins, evolutionary dynamics, and ecological features of microbial mutualism. We touch on gaps in our current understanding of microbial mutualisms, note connections to mutualism in nonmicrobial systems, and call attention to open questions ripe for future study. Expected final online publication date for the Annual Review of Ecology, Evolution, and Systematics, Volume 52 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.


2017 ◽  
Vol 14 (S339) ◽  
pp. 106-109
Author(s):  
G. Mathys

AbstractRecent studies have revealed the existence of a significant population of Ap stars with extremely long rotation periods, and the frequent occurrence of Ap stars in wide binaries. Those results represent new constraints on the understanding of the origin and evolution of Ap stars, and (by extension) of all upper-main-sequence stars. Current knowledge of Ap stars with the longest rotation and orbital periods remains incomplete, on the one hand because in many cases the periods of interest are longer than the time-spans over which relevant observations have been obtained, and on the other hand because some important subsets of Ap stars have been omitted from the studies that have been carried out until now. Additional observations over time-scales of decades to centuries are needed to complement the current incomplete picture. Securing them with the required accuracy and time coverage, and ensuring that their full exploitation will ultimately be possible, represents a unique challenge in time-domain astronomy.


2018 ◽  
Vol 92 (13) ◽  
Author(s):  
Ianei de Oliveira Carneiro ◽  
Anna-Lena Sander ◽  
Namá Silva ◽  
Andres Moreira-Soto ◽  
Andrea Normann ◽  
...  

ABSTRACT The discovery of highly diverse nonprimate hepatoviruses illuminated the evolutionary origins of hepatitis A virus (HAV) ancestors in mammals other than primates. Marsupials are ancient mammals that diverged from other Eutheria during the Jurassic. Viruses from marsupials may thus provide important insight into virus evolution. To investigate Hepatovirus macroevolutionary patterns, we sampled 112 opossums in northeastern Brazil. A novel marsupial HAV (MHAV) in the Brazilian common opossum ( Didelphis aurita ) was detected by nested reverse transcription-PCR (RT-PCR). MHAV concentration in the liver was high, at 2.5 × 10 9 RNA copies/g, and at least 300-fold higher than those in other solid organs, suggesting hepatotropism. Hepatovirus seroprevalence in D. aurita was 26.6% as determined using an enzyme-linked immunosorbent assay (ELISA). Endpoint titers in confirmatory immunofluorescence assays were high, and marsupial antibodies colocalized with anti-HAV control sera, suggesting specificity of serological detection and considerable antigenic relatedness between HAV and MHAV. MHAV showed all genomic hallmarks defining hepatoviruses, including late-domain motifs likely involved in quasi-envelope acquisition, a predicted C-terminal pX extension of VP1, strong avoidance of CpG dinucleotides, and a type 3 internal ribosomal entry site. Translated polyprotein gene sequence distances of at least 23.7% from other hepatoviruses suggested that MHAV represents a novel Hepatovirus species. Conserved predicted cleavage sites suggested similarities in polyprotein processing between HAV and MHAV. MHAV was nested within rodent hepatoviruses in phylogenetic reconstructions, suggesting an ancestral hepatovirus host switch from rodents into marsupials. Cophylogenetic reconciliations of host and hepatovirus phylogenies confirmed that host-independent macroevolutionary patterns shaped the phylogenetic relationships of extant hepatoviruses. Although marsupials are synanthropic and consumed as wild game in Brazil, HAV community protective immunity may limit the zoonotic potential of MHAV. IMPORTANCE Hepatitis A virus (HAV) is a ubiquitous cause of acute hepatitis in humans. Recent findings revealed the evolutionary origins of HAV and the genus Hepatovirus defined by HAV in mammals other than primates in general and in small mammals in particular. The factors shaping the genealogy of extant hepatoviruses are unclear. We sampled marsupials, one of the most ancient mammalian lineages, and identified a novel marsupial HAV (MHAV). The novel MHAV shared specific features with HAV, including hepatotropism, antigenicity, genome structure, and a common ancestor in phylogenetic reconstructions. Coevolutionary analyses revealed that host-independent evolutionary patterns contributed most to the current phylogeny of hepatoviruses and that MHAV was the most drastic example of a cross-order host switch of any hepatovirus observed so far. The divergence of marsupials from other mammals offers unique opportunities to investigate HAV species barriers and whether mechanisms of HAV immune control are evolutionarily conserved.


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