Eye Color Change Research Articles

A simple Schiff base as selective and sensitive fluorescent-colorimetric hydrazine chemosensor

ABSTRACTA new fluorescent-colorimetric chemosensor L has been synthesised by Schiff base condensation reaction between 1,8-diaminooctane and 4-nitro-benzaldehyde in very good yields. Its photo-luminescent properties and selective detection properties for hydrazine have been examined. The synthesised chemosensor exhibited highly selective fluorescence on-off response for hydrazine amongst a wide range of different metal cations, anions and amines, along with the bare eye colour change from colourless to yellow based on intermolecular hydrogen-bond interaction. The limit of detection of the chemosensor L was estimated as 9.77 × 10−8 M or 3.12 × 10−6 g L−1 for hydrazine which is extremely below the limit set by the World Health Organization (WHO) and the binding stoichiometry was proposed to be 1 : 2 based on 1H NMR spectroscopic techniques and the Job’s plot analysis. The proposed sensing mechanism is the hydrogen-bonding interaction which has further been established by Density Functional Theory (Functional Density Theory (DFT)) studies. This recognition feature of sensor L makes it an efficient chemosensor for hydrazine detection in different water samples.

Salen Type Ligand as a Selective and Sensitive Nickel(II) ion Chemosensor: A Combined Investigation with Experimental and Theoretical Modelling

A novel tetradentate (N,O)-donor salen type Schiff base was designed, prepared and structurally characterized by different analytical techniques. This Schiff base ligand, (L = 2,2'-((1,2 phenylenebis(methanylylidene))bis(azanylylidene))diphenol) behaved as an effective chemosensor towards Ni(II) ion with specific selectivity. The Schiff base (L) displayed a remarkable ratiometric fluorescence enhancement upon binding with Ni(II) ion in acetonitrile (ACN) medium. The L-Ni(II) solution was distinguished indisputably with the naked eye colour change and the crystal was found to be red colour. L selectively detected Ni(II) ion in presence of other competitive cations like Mn(II), Fe(II),Co(II), Cu(II), Zn(II), Cd(II) and Hg(II) ions. This simple but novel Schiff base might be used as a potential pH independent colorimetric and naked-eye chemosensor for Ni(II) ion. Most significantly, L exhibited geometry preferred selectivity towards Ni(II) ion and formed highly stable square planar Ni(II)-Schiff base complex. Single crystal X-ray diffraction study further authenticated that the nickel complex crystallized in orthorhombic system with P212121 space group in solid state. Density functional theory (DFT) calculations attested the experimental results very well. This sensing method could be applied in a wider concentration range and might be used as an alternative qualitative and quantitative test for the detection of Ni(II) ion in analytical chemistry.

Harvesting procedures, welfare and shelf life of ungutted and gutted shortfin pompano (Trachinotus falcatus) stored in ice

Shortfin pompano (Trachinotus falcatus) were harvested from a floating cage culture. Handling stress (blood pH, white muscle pH, and rigor mortis) and welfare (“eye roll”) were determined for two harvesting methods: (i) batch netting and transfer to ice-slurry where the fish were killed and chilled (commercial method) and, (ii) transfer of fish to a tub immersed in the cage before it was lifted onto a barge where the fish were euthanised by an AQUI-S™ overdose. Half of the ice-slurry fish were gutted. All fish were subsequently stored for 18 d in ice for assessment of freshness (total bacterial counts, TBC and Quality Index Method, QIM) as well as skin and eye color. A modified QIM scheme for European sea bass was used with demerit points ranging from 0 to 18. Due to excessive swimming during crowding, both ice-slurry and AQUI-S™ fish were harvested in an exhausted condition. Upon sampling, none of the fish exhibited “eye roll”, indicating they were either unconscious or dead. Since the ice-slurry fish were not stunned immediately, the welfare of the fish might have been compromised. During rapid chilling, the fish developed cloudy eyes. The asset of using AQUI-S™ was possibly better fish welfare during the stunning and euthanising phase since exposure to ice-slurry was associated with escape swimming behaviour and slow death. Shortly after harvesting there were some significant differences between harvesting methods in terms of skin color. They were, however, largely offset by storage for one day. Only a few minor changes in skin color took place during further storage. Changes in eye color were more prominent than for skin. After storage for more than a week, the TBCs of gutted fish were significantly higher compared with ungutted fish (P <0.05). AQUI-S™ fish (ungutted) exhibited the lowest TBCs for about the first two weeks indicating exposure to the anesthetic reduced bacterial growth. After 18 d, none of fish from all treatments had yet reached the generally accepted spoilage level of 7 log cfu g−1. At this point, the fish had not reached the maximum attainable QI score of 18. High linear correlations (R ≥ 0.972, P < 0.001) were achieved for development of QI during ice storage where the ungutted and AQUI-S™ treatments were practically similar. The modified QIM scheme was considered suitable for pompano. The shelf life was tentatively considered to be approximately 18 d, although this should to be verified by other, supplementary methods. To prolong shelf life, it is recommended that pompano is not gutted before they are subjected to chilled storage.

A real-time tripodal colorimetric/fluorescence sensor for multiple target metal ions

In this work we report on the synthesis of a pyridyl/phenolic/benzothiazole functionalized colorimetric receptor (BPAP) that can selectively recognise Fe(III) and Fe(II) ions in aqueous medium with visible, naked eye colour changes. Moreover, BPAP behaves as a ‘turn-on’ fluorescent chemosensor, showing an excellent sensitivity towards Zn2+ and Cd2+ cations in water by exhibiting fluorometric change. BPAP exhibited a visible detection limit of 5.5 μM and 2.5 μM for Fe3+ and Fe2+, respectively, and a fluorometric selectivity towards Zn2+ and Cd2+ ions with lower detection limits of 205 nM and 642 nM. To understand the mode of binding to the sensor, both the nude sensor and the Zn-complex were isolated and characterized by X-ray crystallography. In Zn-BPAP, the ligand acts as neutral tridentate through Npyridine, Namine and Namide donor atoms. The N atom of benzothiazole group and the OH group of the phenole unit are not coordinated. Computational DFT study was performed on the free ligand BPAP and complex with Zn2+ to investigate the interaction site, to calculate the energies of the frontier molecular orbitals and to corroborate some of the experimental results.

Instilling exploitable INHIBIT logic gate response for F−/H+ in ‘end-off’ anthracene-diamine hybrid by simple functional group manipulation: Experimental study aided by DFT calculations

Two anthracene based receptors ADAMN and ANOPD were synthesized and characterized. The response of both towards F− ion has been monitored by UV–Vis and 1H NMR spectroscopy as well as naked eye color change. Interestingly, change in acceptor unit endows ADAMN to behave as a INHIBIT logic gate with F− and H+ as inputs whereas ANOPD remains totally silent towards F−. The reason for this differential behavior has been explored by DFT calculations. The practical utility of the logic gate response of ADAMN was explored by successful paper strip experiment.

Hydrazine appended self assembled benzoin-naphthalene conjugate as an efficient dual channel probe for Cu2+ and F−: A spectroscopic investigation with live cell imaging for Cu2+ and practical performance for fluoride

We report the synthesis of a novel hydrazine based compound 1-[(2-Hydroxy-1, 2-diphenyl-ethyl)-hydrazonomethyl]-naphthalen-2-ol (2). Compound 2 is the first report of its kind. We utilized the aforesaid compound to detect Cu2+ and F− via emission enhancement and naked eye color change. The structural intricacies of 2 have been explored by its crytal structure. The mechanism of binding of 2 with F− has been established by 1H NMR titration. The limit of detection for Cu2+ and F− is ∼9.0 × 10−7 (M) and 1.0 × 10−6 (M), respectively. The practical performance of 2 is demonstrated by successful live cell imaging of Cu2+ and detection of F− in toothpaste.

What colour are newborns' eyes? Prevalence of iris colour in the Newborn Eye Screening Test (NEST) study.

This study aims to assess the birth prevalence of iris colour among newborns in a prospective, healthy, full-term newborn cohort. The Newborn Eye Screening Test (NEST) study is a prospective cohort study conducted at Lucile Packard Children's Hospital at Stanford University School of Medicine. A paediatric vitreoretinal specialist (DMM) reviewed images sent to the Byers Eye Institute telemedicine reading centre and recorded eye colour for every infant screened. Variables were graphed to assess for normality, and frequencies per subject were reported for eye colour, sex, ethnicity and race. Among 192 subjects screened in the first year of the NEST study with external images of appropriate quality for visualization of the irides, the birth prevalence of iris colour was 63.0% brown, 20.8% blue, 5.7% green/hazel, 9.9% indeterminate and 0.5% partial heterochromia. The study population was derived from a quaternary care children's hospital. We report the birth prevalence of iris colour among full-term newborns in a diverse prospective cohort. The study demonstrates a broad range of iris colour prevalence at birth with a predominance of brown iris coloration. Future studies with the NEST cohort will assess the change in iris colour over time and whether the frequencies of eye colour change as the child ages.

Selective chromo-fluorogenic molecular sensor for dual channel recognition of Cu2+and F−: effect of functional group on selectivity

The amido-Schiff base (3-hydroxy-naphthalene-2-carboxylic acid(4-cyano-benzylidene)-hydrazide) shows dual mode sensibility towards Cu2+and F−. It can detect Cu2+in HEK 293 cells and F−in tooth paste and in solid state.

Simple naked-eye ratiometric and colorimetric receptor for anions based on azo dye featuring with benzimidazole unit

A simple, tailor made receptor 2 based on azo dye featuring with benzimidazole unit with hybrid –OH and –NH binding sites was synthesized and characterized. The addition of CN−, AcO−, F−, and H2PO4− in acetonitrile solution of 2 resulted in a large bathochromic shift from 315nm to 470nm allowing naked eye color change from colorless to orange. Anion sensing characteristics were determined using visual inspection, UV–vis and 1H NMR spectroscopy pointing toward the improved chromogenic ability after introduction of NN group in the azo dye 2. The mechanism of anion binding with receptor 2 showed 1:2 (L/Anion) and the association constants were found in the order of AcO−>CN−>F−>H2PO4−.

Age- and temperature-related pupal eye colour changes in various tephritid fruit fly species with a view to optimizing irradiation timing

The application of the sterile insect technique to fruit flies involves the mass-production of the pest insects using an artificial diet, irradiation during a narrow time window at the late pupal or early imaginal stage to inhibit reproduction without affecting reproductive capacity, and then release into the target area where the sterile insects compete reproductively with their wild counterparts. The timing of irradiation is important to enable the release of males that are sterile but of good quality and exhibit an acceptable sexual performance. In this study, we examined the pupal development of 12 tephritid (Diptera: Tephritidae) species: Anastrepha fraterculus (Wiedemann), A. ludens (Loew), A. obliqua (Macquart), A. serpentina (Wiedemann), Bactrocera cucurbitae (Coquillett), B. dorsalis (Hendel), B. invadens (Drew, Tsuruta & White), B. oleae (Rossi), B. philippinensis (Drew & Hancock), B. tryoni (Froggatt), B. zonata (Saunders) and Ceratitis capitata (Wiedemann). The insects were reared at various temperatures, in the laboratory (15–28 °C) and under fluctuating natural conditions (20–35 °C). The gradual colour changes of the insect eyes during metamorphosis were observed and photographed, measuring the specific eye colour parameters of each species and matching them with the colour scale of the Munsell Soil Color Charts. The duration of pupal development and the time to emergence in Anastrepha species were longer than those in C. capitata and Bactrocera species at all the holding temperatures. The data obtained can be used by mass-rearing facilities to manage pupal holding conditions and as indicators for optimizing the timing of irradiation.

Calix[4]arene based molecular probe for sensing copper ions

A novel calix[4]arene based molecular probe for metal ions has been designed, synthesized and evaluated. Studies on its binding with different metal ions reveal a noticeable naked eye color change, bathochromic shift in absorption spectrum and remarkable enhancement in fluorescence emission in the presence of Cu2+ only. The role of calix[4]arene scaffold for selective recognition of Cu2+ has been demonstrated by repeat evaluation and analysis of an appropriate reference molecule. A rational explanation for fluorescence enhancement in 3 on interaction with copper has been suggested.

Circadian rhythms affect electroretinogram, compound eye color, striking behavior and locomotion of the praying mantis Hierodula patellifera.

Many behaviors and physiological processes oscillate with circadian rhythms that are synchronized to environmental cues (e.g. light onset), but persist with periods of ~24 h in the absence of such cues. We used a multilevel experimental approach to assess whether circadian rhythms modulate several aspects of the visual physiology and behavior of the praying mantis Hierodula patellifera. We used electroretinograms (ERGs) to assess compound eye sensitivity, colorimetric photographic analyses to assess compound eye color changes (screening pigment migration), behavioral assays of responsiveness to computer-generated prey-like visual stimuli and analyses of locomotor activity patterns on a modified treadmill apparatus. Our results indicate that circadian clocks control and/or modulate each of the target behaviors. Strong rhythms, persisting under constant conditions, with periods of ~24 h were evident in photoreceptor sensitivity to light, appetitive responsiveness to prey-like stimuli and gross locomotor activity. In the first two cases, responsiveness was highest during the subjective night and lowest during the subjective day. Locomotor activity was strongly clustered around the transition time from day to night. In addition, pigment migration and locomotor behavior responded strongly to light:dark cycles and anticipated the light-dark transition, suggesting that the circadian clocks modulating both were entrained to environmental light cues. Together, these data indicate that circadian rhythms operate at the cellular, cellular systems and organismal level in H. patellifera. Our results represent an intriguing first step in uncovering the complexities of circadian rhythms in the Mantodea.

Freshness assessment of gilthead sea bream (Sparus aurata) by machine vision based on gill and eye color changes

The fish freshness was evaluated using machine vision technique through color changes of eyes and gills of farmed and wild gilthead sea bream (Sparus aurata), being employed lightness (L*), redness (a*), yellowness (b*), chroma (c*), and total color difference (ΔE) parameters during fish ice storage. A digital color imaging system, calibrated to provide accurate CIELAB color measurements, was employed to record the visual characteristics of eyes and gills. The region of interest was automatically selected using a computer program developed in MATLAB software. L*, b*, and ΔE of eyes increased with storage time, while c* decreased. The a* parameter of fish eyes did not show clear a trend with storage time. The L*, b*, and ΔE of fish gills increased with storage time, but a* and c* decreased. Regression analysis and artificial neural networks approaches were used to correlate the eyes and gills color parameters with the time of storage and a strong correlation was found between color parameters and storage day. Gills color changes were more precise than those found for eyes in order to evaluate the fish freshness. However, the gills cover should be removed for taking the images and thus, the method is destructive and time-consuming. Therefore, the color parameters of fish eyes can be used as a green, low cost and easy method for fast and on-line assessing of fish freshness in food industry.

‘PET’ vs. ‘push–pull’ induced ICT: a remarkable coumarinyl-appended pyrimidine based naked eye colorimetric and fluorimetric sensor for the detection of Hg2+ ions in aqueous media with test trips

A novel colorimetric and fluorescent chemosensor based on 7-(diethylamino)-3-(pyrimidin-4-yl)-2H-chromen-2-one (PYC) has been designed and synthesized for the detection of Hg(2+) in the presence of other competing metals in mixed aqueous media. The PYC exhibits naked eye color change from green to red, and the fluorescence color changes from yellowish green to light orange with Hg(2+). It also shows a red shift in wavelength of about 80 nm in absorption spectra. Test strips based on PYC were fabricated, which could act as convenient and efficient Hg(2+) test kits.

A Highly Selective Colorimetric Chemosensor for Mn2+ Based on Bis(N-salicylidene)ethylenediamine in Pure Aqueous Solution

Abstract A novel easily available chemosensor 1 based on bis(N-salicylidene)ethylenediamine was reported, which exhibits highly selective and sensitive recognition toward Mn2+ in pure aqueous solution over a wide range of tested metal ions with a clear naked eye color change from colorless to red. This represents the first reported colorimetric chemosensor capable of detecting Mn2+ in aqueous solution.

A highly selective chemosensor for Cu2+ and Al3+ in two different ways based on Salicylaldehyde Schiff

Abstract A novel, easily available colorimetric and fluorescent double-sensor 1 based on Salicylaldehyde bis-Schiff has been investigated in this work. The sensor exhibits highly selective and sensitive recognition toward Cu2+ in aqueous solution via a naked eye colour change from colourless to yellow and toward Al3+ via a significant fluorescent enhancement in ethanol over a wide range of tested metal ions. This represents the first reported Salicylaldehyde Schiff-based sensor capable of detecting both Cu2+ and Al3+ using two different modes.

Presence of a conspecific causes divergent changes in resting metabolism, depending on its relative size

It is well established that the average metabolism of many species of fish varies with group size. However, it is not clear whether all individuals respond in the same way. Here, we use a newly calibrated method of measuring the metabolic rate of fish from opercular (ventilatory) movements that allows for the first-time estimation of changes in resting metabolic rate (RMR) of each individual within different social groups and when alone. The presence of a conspecific had divergent effects on the RMR of juvenile Atlantic salmon Salmo salar, depending on its relative body size: the presence of a smaller fish caused a 40 per cent reduction, whereas the presence of a slightly larger fish approximately doubled RMR. These effects occurred in the absence of activity and were sustained at lower magnitude in the case of the relatively smaller conspecific even if a transparent barrier prevented any physical interactions between fish. Changes in RMR were mirrored by changes in eye colour that indicate they were linked to stress levels. These contrasting and strong responses show that even the nearby presence of a conspecific can have profound and variable effects on an individual's energy budget; they also highlight the complex trade-offs involved in social interactions.

Eye Colour, Aging, and Decoy Trap Bias in Lesser Scaup, &lt;em&gt;Aythya affinis&lt;/em&gt;

Researchers routinely assume that samples of trapped or captured animals are representative of the overall population, though these assumptions are not always evaluated. We used decoy-trapped Lesser Scaup (Aythya affinis) to assess the reliability of classifying females as yearlings or adults from a distance, based on documented age-related eye-colour changes, and also to evaluate the presence of sex, condition and age biases in decoy trapping. We compared eye colour of trapped females to photographs of known-age females following a published procedure while females were (1) in traps (by using spotting scopes or binoculars) and (2) in-hand. Assuming in-hand age assessments were correct, we found that adults aged from a distance were frequently misclassified as yearlings, but yearlings were never misclassified as adults. Distance between observer and female, overall observation quality, and cloud cover did not influence age assignment success. A larger proportion of males was captured than observed during a survey of the local breeding population. We also found that decoy-trapped females had lower body mass and were more likely to be yearlings compared to pass- and jump-shot females from the same area. We conclude that female Lesser Scaup cannot be accurately aged from a distance using eye colour and concur with other researchers that possible sex, age and condition biases should be evaluated when using decoy traps.

Thepinkgene encodes theDrosophilaorthologue of the human Hermansky–Pudlak syndrome 5 (HPS5) gene

Hermansky-Pudlak syndrome (HPS) consists of a set of human autosomal recessive disorders, with symptoms resulting from defects in genes required for protein trafficking in lysosome-related organelles such as melanosomes and platelet dense granules. A number of human HPS genes and rodent orthologues have been identified whose protein products are key components of 1 of 4 different protein complexes (AP-3 or BLOC-1, -2, and -3) that are key participants in the process. Drosophila melanogaster has been a key model organism in demonstrating the in vivo significance of many genes involved in protein trafficking pathways; for example, mutations in the "granule group" genes lead to changes in eye colour arising from improper protein trafficking to pigment granules in the developing eye. An examination of the chromosomal positioning of Drosophila HPS gene orthologues suggested that CG9770, the Drosophila HPS5 orthologue, might correspond to the pink locus. Here we confirm this gene assignment, making pink the first eye colour gene in flies to be identified as a BLOC complex gene.

Changes in eye colour of juvenile Bearded Tits Panurus biarmicus and its use in determining breeding productivity

IbisVolume 149, Issue 2 p. 407-411 Changes in eye colour of juvenile Bearded Tits Panurus biarmicus and its use in determining breeding productivity JOHN WILSON, JOHN WILSON 40 Church Hill Avenue, Warton, Carnforth, Lancashire LA5 9NU, UKSearch for more papers by this authorIAN R. HARTLEY, Corresponding Author IAN R. HARTLEY Biological Sciences, Lancaster University, Lancaster LA1 4YQ, UK *Corresponding author. Email: i.hartley@lancaster.ac.ukSearch for more papers by this author JOHN WILSON, JOHN WILSON 40 Church Hill Avenue, Warton, Carnforth, Lancashire LA5 9NU, UKSearch for more papers by this authorIAN R. HARTLEY, Corresponding Author IAN R. HARTLEY Biological Sciences, Lancaster University, Lancaster LA1 4YQ, UK *Corresponding author. Email: i.hartley@lancaster.ac.ukSearch for more papers by this author First published: 22 January 2007 https://doi.org/10.1111/j.1474-919X.2006.00630.xCitations: 7Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume149, Issue2April 2007Pages 407-411 RelatedInformation