scholarly journals Retinal transcriptome sequencing sheds light on the adaptation to nocturnal and diurnal lifestyles in raptors

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Yonghua Wu ◽  
Elizabeth A. Hadly ◽  
Wenjia Teng ◽  
Yuyang Hao ◽  
Wei Liang ◽  
...  
Keyword(s):  
Positive Selection ◽  
Transcriptome Sequencing ◽  
Bright Light ◽  
Photon Absorption ◽  
Evolutionary Analysis ◽  
Night Time ◽  
Low Light ◽  
Strong Positive Selection ◽  
Nocturnal Vision ◽  
Selection For

Abstract Owls (Strigiformes) represent a fascinating group of birds that are the ecological night-time counterparts to diurnal raptors (Accipitriformes). The nocturnality of owls, unusual within birds, has favored an exceptional visual system that is highly tuned for hunting at night, yet the molecular basis for this adaptation is lacking. Here, using a comparative evolutionary analysis of 120 vision genes obtained by retinal transcriptome sequencing, we found strong positive selection for low-light vision genes in owls, which contributes to their remarkable nocturnal vision. Not surprisingly, we detected gene loss of the violet/ultraviolet-sensitive opsin (SWS1) in all owls we studied, but two other color vision genes, the red-sensitive LWS and the blue-sensitive SWS2, were found to be under strong positive selection, which may be linked to the spectral tunings of these genes toward maximizing photon absorption in crepuscular conditions. We also detected the only other positively selected genes associated with motion detection in falcons and positively selected genes associated with bright-light vision and eye protection in other diurnal raptors (Accipitriformes). Our results suggest the adaptive evolution of vision genes reflect differentiated activity time and distinct hunting behaviors.

scholarly journals The effect of blue-blocking lenses on photostress recovery times for low and high contrast chromatic and achromatic stimuli

2019 ◽  
Author(s):  
Hind Saeed Alzahrani ◽  
Sieu K. Khuu ◽  
Adiba Ali ◽  
Maitreyee Roy
Keyword(s):  
Light Exposure ◽  
Bright Light ◽  
Light Sources ◽  
High Contrast ◽  
Night Time ◽  
Low Light ◽  
Low Contrast ◽  
Light Levels ◽  
Recovery Times ◽  
Visible Wavelengths

AbstractThe selective reduction in visible wavelengths transmitted through commercially available blue-blocking lenses (BBLs) is known to influence the appearance and contrast detection of objects, particularly at low light levels which may impact the human retinal receptor response time to dynamic light changes during phostress events. In the present study, we assessed whether BBLs selectively affect photostress recovery times (PSRTs) in 12 participants for chromatic and achromatic stimuli presented under low and high contrast luminance conditions. Four types of commercially available BBLs were evaluated, and their effects on PSRTs were investigated. Our results showed that PSRTs required to detect high contrast chromatic and achromatic stimuli were unaffected by BBLs when compared to a clear control lens. However, PSRTs were significantly affected by BBLs and were longer when chromatic and achromatic stimuli were of low contrast. In addition, BBLs had the greatest impact on the PSRTs of blue coloured targets, and this was dependent on the spectral transmittance profile. These results indicate that wearing BBLs under low contrast conditions can have serious implications for visual behavior, particularly under low-light levels and in situations in which the observer is directly exposed to bright light sources. For example, during night time driving, the driver might be briefly exposed to bright lights by glancing at the headlights of a passing car. This increases the time required for vision to be restored after bright light exposure, resulting in delayed object detection, and therefore stoppage and reaction times, which might pose a safety risk for a driver.

Parental Care, Destabilizing Selection, and the Evolution of Tetrapod Endothermy

Physiology ◽  
2020 ◽  
Vol 35 (3) ◽  
pp. 160-176 ◽  
Author(s):  
C. G. Farmer
Keyword(s):  
Parental Care ◽  
Positive Selection ◽  
Convergent Evolution ◽  
Terrestrial Environment ◽  
Strong Positive Selection ◽  
Selection For ◽  
Destabilizing Selection

Parental care has evolved convergently an extraordinary number of times among tetrapods that reproduce terrestrially, suggesting strong positive selection for this behavior in the terrestrial environment. This review speculates that destabilizing selection on parental care, and especially embryo incubation, drove the convergent evolution of many tetrapod traits, including endothermy.

scholarly journals Revisiting the evolutionary analysis of mammalian CRISPs reveals positive selection

2018 ◽  
Author(s):  
Alberto Vicens ◽  
Claudia Treviño
Keyword(s):  
Positive Selection ◽  
Adaptive Evolution ◽  
Negative Selection ◽  
Secretory Proteins ◽  
Evolutionary Analysis ◽  
Episodic Selection ◽  
Show Evidence ◽  
Selection For ◽  
Related Proteins

AbstractCysteine-rich secretory proteins (CRISPs) constitute a versatile family, with functions that include being components of reptilian venom and participation in mammalian reproduction. While non-mammalian vertebrates express a single CRISP gene, mammals generally express three CRISP paralogs. A previous study assessing the molecular evolution of vertebrate CRISPs revealed strong positive selection in reptilian CRISP and negative selection in mammalian CRISPs. In this study, we re-assessed molecular adaptation of mammalian CRISPs through an analysis of larger sequence datasets that represent mammalian diversity. Our analyses show evidence of recent episodes of positive selection for all mammalian CRISPs. Intensity of positive selection was heterogeneous both among CRISP paralogs (being stronger in CRISP3 than in CRISP1 and CRISP2) and across functional domains (having more impact on CRD or PR-1 domain). Analysis of episodic selection did not yield strong signatures of adaptive evolution in any particular mammalian group, suggesting that positive selection was more pervasive on mammalian CRISPs. Our findings provide evidence of adaptive evolution in a family of reproduction-related proteins, and offer interesting insights regarding the role of mammalian CRISPs in fertility and speciation.

scholarly journals Photogrammetric Digital Surface Model Reconstruction in Extreme Low-Light Environments

2021 ◽  
Vol 13 (7) ◽  
pp. 1261
Author(s):  
Riccardo Roncella ◽  
Nazarena Bruno ◽  
Fabrizio Diotri ◽  
Klaus Thoeni ◽  
Anna Giacomini
Keyword(s):  
Image Quality ◽  
Image Quality Assessment ◽  
High Sensitivity ◽  
Sensor Technology ◽  
Surface Model ◽  
Night Time ◽  
Low Light ◽  
Reduction Techniques ◽  
Geometrical Information ◽  
Imaging Sensors

Digital surface models (DSM) have become one of the main sources of geometrical information for a broad range of applications. Image-based systems typically rely on passive sensors which can represent a strong limitation in several survey activities (e.g., night-time monitoring, underground survey and night surveillance). However, recent progresses in sensor technology allow very high sensitivity which drastically improves low-light image quality by applying innovative noise reduction techniques. This work focuses on the performances of night-time photogrammetric systems devoted to the monitoring of rock slopes. The study investigates the application of different camera settings and their reliability to produce accurate DSM. A total of 672 stereo-pairs acquired with high-sensitivity cameras (Nikon D800 and D810) at three different testing sites were considered. The dataset includes different camera configurations (ISO speed, shutter speed, aperture and image under-/over-exposure). The use of image quality assessment (IQA) methods to evaluate the quality of the images prior to the 3D reconstruction is investigated. The results show that modern high-sensitivity cameras allow the reconstruction of accurate DSM in an extreme low-light environment and, exploiting the correct camera setup, achieving comparable results to daylight acquisitions. This makes imaging sensors extremely versatile for monitoring applications at generally low costs.

Photoinhibition of DCMU-Enhanced Fluorescence in Lake Ontario Phytoplankton

1987 ◽  
Vol 44 (12) ◽  
pp. 2144-2154 ◽  
Author(s):  
M. Putt ◽  
G. P. Harris ◽  
R. L. Cuhel
Keyword(s):  
Vertical Mixing ◽  
Natural Populations ◽  
Bright Light ◽  
Euphotic Zone ◽  
Lake Ontario ◽  
Enhanced Fluorescence ◽  
Low Light ◽  
Light Levels ◽  
Phosphorus Status

Measurement of 1-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) enhanced fluorescence (FDCMU) suggested that photoinhibition of photosynthesis was frequently an artifact of in situ bottle incubations in Lake Ontario phytoplankton. In a seasonal study, FDCMU of all populations was depressed by bright light in an incubator. However, when the euphotic zone did not exceed the depth of the mixed layer, vertical transport of phytoplankton into either low-light or dark regions apparently allowed reversal of photoinhibition of FDCMU. Advantages of FDCMU as a bioassay of vertical mixing include rapidity of response time, ease of measurement in the field, and insensitivity of this parameter to changes in phosphorus status of the population. Because of seasonal changes in the photoadaptive response of natural populations, the rate constants and threshold light levels required to cause the response must be determined at each use if the method is to be quantitative.

scholarly journals A novel positive selection for identifying cold-sensitive myosin II mutants in Dictyostelium.

Genetics ◽  
1995 ◽  
Vol 140 (2) ◽  
pp. 505-515 ◽  
Author(s):  
B Patterson ◽  
J A Spudich
Keyword(s):  
Positive Selection ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Time Scale ◽  
Myosin Ii ◽  
Rapid Onset ◽  
Chemical Mutagenesis ◽  
Wild Type ◽  
Cold Sensitive ◽  
Selection For

Abstract We developed a positive selection for myosin heavy chain mutants in Dictyostelium. This selection is based on the fact that brief exposure to azide causes wild-type cells to release from the substrate, whereas myosin null cells remain adherent. This procedure assays myosin function on a time scale of minutes and has therefore allowed us to select rapid-onset cold-sensitive mutants after random chemical mutagenesis of Dictyostelium cells. We developed a rapid technique for determining which mutations lie in sequences of the myosin gene that encode the head (motor) domain and localized 27 of 34 mutants to this domain. We recovered the appropriate sequences from five of the mutants and demonstrated that they retain their cold-sensitive properties when expressed from extrachromosomal plasmids.

scholarly journals Is formal employment sector hereditary? Determinants of formal/informal sector choice for Mexican male workers

2019 ◽  
pp. 91-121
Author(s):  
Adelaido García-Andrés ◽  
Ernesto Aguayo-Téllez ◽  
Jose N. Martínez
Keyword(s):  
Positive Selection ◽  
Social Mobility ◽  
Informal Sector ◽  
Formal Sector ◽  
Strong Connection ◽  
Employment Sector ◽  
Formal Employment ◽  
Selection For ◽  
The Relationship ◽  
Employment Choices

Understanding the relationship between parents’ and sons’ formal employment is essential for promoting social mobility in Mexico. Using the 2011 Survey of Social Mobility in Mexico (EMOVI), this paper contributes to the literature by addressing the intergenerational mobility of employment. Findings show a strong connection between intergenerational employment choices and suggest a positive selection for workers. Individuals with parents who worked in the formal sector are more likely to be enrolled in formal work and vice versa. Also, after controlling for parent’s employment sector, schooling remains as a significant vehicle to transit to the formal sector.

scholarly journals Positive Selection on Two Mitochondrial Coding Genes and Adaptation Signals in Hares (Genus Lepus) from China

2020 ◽  
Author(s):  
Asma Awadi ◽  
Hichem Ben Slimen ◽  
Helmut Schaschl ◽  
Felix Knauer ◽  
Franz Suchentrunk
Keyword(s):  
Amino Acid ◽  
Positive Selection ◽  
Protein Function ◽  
Transmembrane Domain ◽  
Proton Translocation ◽  
Introgressive Hybridization ◽  
Vibrational Entropy ◽  
Mutant Type ◽  
Selection For ◽  
Protein Variants

Abstract Background: Animal mitochondria play a central role in energy production in the cells through the oxidative phosphorylation (OXPHOS) pathway. Recent studies of selection on different mitochondrial OXPHOS genes have revealed the adaptive implications of amino acid changes in these subunits. In hares, climatic variation and/or introgression were suggested to be at the origin of such adaptation. Here we looked for evidence of positive selection in three mitochondrial OXPHOS genes, using tests of selection, protein structure modelling and effects of amino acid substitutions on the protein function and stability. We also used statistical models to test for climate and introgression effects on sites under positive selection. Results: Our results revealed seven sites under positive selection in ND4 and three sites in Cytb. However, no sites under positive selection were observed in the COX1 gene. All three subunits presented a high number of codons under negative selection. Sites under positive selection were mapped on the tridimensional structure of the predicted models for the respective mitochondrial subunit. Of the ten amino acid replacements inferred to have evolved under positive selection for both subunits, six were located in the transmembrane domain. On the other hand, three codons were identified as sites lining proton translocation channels. Furthermore, four codons were identified as destabilizing with a significant variation of Δ vibrational entropy energy between wild and mutant type. Moreover, the PROVEAN analysis suggested that among all positively selected sites two fixed amino acid replacements altered the protein functioning. The statistical model runs indicated significant effects of climate on the presence of ND4 and Cytb protein variants, but no effect by trans-specific mitochondrial DNA introgresson.Conclusions: Positive selection was observed in several codons in two OXPHOS genes. We found that substitutions in the positively selected codons have structural and functional impacts on the encoded proteins. Our results are concordantly suggesting that adaptations have strongly affected the evolution of mtDNA of hare species with potential effects on the protein function. Environmental/climatic changes appear to be a major trigger of this adaptation, whereas trans-specific introgressive hybridization seems to play no major role for the occurrence of protein variants.

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