Comparative Behavior of \u3ci\u3ePyrellia Cyanicolor\u3c/i\u3e (Diptera: Muscidae) on the Moss \u3ci\u3eSplachnum Ampullaceum\u3c/i\u3e and on Substrates of Nutritional Value

(excerpt) Entomophily is commonly associated with flowering plants and their pollen vectors, but also occurs in other groups of plants. Among fungi, several genera of Phallaceae offer food rewards to calliphorid and muscid flies, which inadvertently disperse the fungal spores (Ingold 1964). Bryhn (1897) first noted a relationship between various species ofDiptera and members of the moss family Splachnaceae. The nature of this interaction has been the subject of much speculation (Bequaert 1921, Erlanson 1935, Crum et aI. 1972, Koponen and Koponen 1977), but no experimental evidence has been collected

Diurnal illumination patterns affect the development of the chick eye

AbstractExposure to continuous illumination disrupts normal ocular development in young chicks, causing severe corneal flattening, shallow anterior chambers and progressive hyperopia (‘constant light (CL) effects’). We have studied the minimum requirements of a diurnal light cycle to prevent CL effects. (1) Seven groups of 10 chicks were reared under a 0 (constant light, CL), or 1, 2, 3,4, 6, or 12/12 h (normal) light–dark cycles. It was found that CL effects were prevented if the dark period was 4 h or longer. Below 4 h, the effects were dose-dependent and inversely correlated with the amplitude of the Fourier component of illumination at 1 cycle per day (CPD). (2) Three groups of 20 chicks were exposed to 4 h of darkness distributed differently over 24 h to vary the amplitude of the Fourier component at 1 CPD. It was found that complete suppression of the CL effects required that the 4 h of darkness were given in one block and at the same time each day. Our results show that normal ocular development in the chick requires a minimum of 4 h darkness per day, provided at the same time of the day without interruption, and suggest that the light–dark cycle interacts with a linear or weakly nonlinear oscillating system

Double-Pass Measurement of Retinal Image Quality in the Chicken Eye

8 pages, 6 figures.-- PMID: 12553544 [PubMed].-- This research was presented as a paper at the annual meeting of the Association for Research in Vision and Ophthalmology on May 4, 2000, in Ft. Lauderdale, FL.[Purpose] The chicken, Gallus gallus domesticus, is used as an animal model to study the development of refractive error. Although vision is important in determining the eye's refractive state, relatively little is known about the retinal image quality of the chicken eye. An objective double-pass technique was used to measure the optical quality of the eyes of White Leghorn chickens.[Methods] Measurements were made on 21 eyes of six untreated birds and eight experimental birds that were members of a study of refractive development. Ages ranged from 3 to 6 weeks, and refractions ranged from -1.29 to +0.58 D in the untreated eyes and -4.58 to +10.17 D in the experimental eyes. The measurements were made under general anesthesia combined with either cycloplegia or ciliary nerve section. Proper optical alignment of the eye was achieved with the aid of a TV monitor, CCD camera, and an infrared source. A 543-nm laser point source was focused on the retina, and the double-pass aerial image was collected by a high-resolution CCD camera. Refractive errors were corrected with trial lenses, using a bracketing method to optimize the retinal images. Both the full width at half-maximum of the double-pass aerial image and the single-pass modulation transfer function were used as objective estimates of the optical quality.[Results] The mean full width at half-maximum value in eyes of the untreated birds was 1.60 min arc for a 4.50-mm mean pupil diameter. Optical quality tended to be worse in the experimental myopic eyes.[Conclusions] The optical quality of the chicken eye measured under monochromatic conditions meets or may even exceed the neural limits of spatial acuity based on anatomical estimates of ganglion cell spacing. The data also suggest that optical quality is worse in myopic eyes, which is consistent with studies of human eyes.Support for this research was provided by National Eye Institute, National Institutes of Health grants EY04395 to S. Burns, EY11228 to D. Troilo, EY12392 to C. Wildsoet, and EY12847 to N. Coletta. S. Marcos was supported by the Human Frontier Science Program LT/0542/1997-B and Fulbright 163/2000.Peer reviewe

COVID-19: Ensuring safe clinical teaching at university optometry schools

The COVID-19 pandemic has been spreading across the globe for several months. The nature of the virus (SARS-CoV-2) with easy person-to-person transmissions and the severe clinical course observed in some people necessitated unprecedented modifications of everyday social interactions. These included the temporary suspension of considerable elements of clinical teaching at optometry schools worldwide. This article describes the challenges optometry schools were facing in early to mid 2020. The paper highlights the experiences of six universities in five countries on four continents. Strategies to minimise the risk of virus transmission, to ensure safe clinical optometric teaching and how to overcome the challenges presented by COVID-19 are described. An outlook on opportunities to further improve optometric education is provided.</p

Gene expression in response to optical defocus of opposite signs reveals bidirectional mechanism of visually guided eye growth

Myopia (nearsightedness) is the most common eye disorder, which is rapidly becoming one of the leading causes of vision loss in several parts of the world because of a recent sharp increase in prevalence. Nearwork, which produces hyperopic optical defocus on the retina, has been implicated as one of the environmental risk factors causing myopia in humans. Experimental studies have shown that hyperopic defocus imposed by negative power lenses placed in front of the eye accelerates eye growth and causes myopia, whereas myopic defocus imposed by positive lenses slows eye growth and produces a compensatory hyperopic shift in refractive state. The balance between these two optical signals is thought to regulate refractive eye development; however, the ability of the retina to recognize the sign of optical defocus and the composition of molecular signaling pathways guiding emmetropization are the subjects of intense investigation and debate. We found that the retina can readily distinguish between imposed myopic and hyperopic defocus, and identified key signaling pathways underlying retinal response to the defocus of different signs. Comparison of retinal transcriptomes in common marmosets exposed to either myopic or hyperopic defocus for 10 days or 5 weeks revealed that the primate retina responds to defocus of different signs by activation or suppression of largely distinct pathways. We also found that 29 genes differentially expressed in the marmoset retina in response to imposed defocus are localized within human myopia quantitative trait loci (QTLs), suggesting functional overlap between genes differentially expressed in the marmoset retina upon exposure to optical defocus and genes causing myopia in humans. These findings identify retinal pathways involved in the development of myopia, as well as potential new strategies for its treatment

Anatomy and Pathology Eyes in Various Species Can Shorten to Compensate for Myopic Defocus

PURPOSE. We demonstrated that eyes of young animals of various species (chick, tree shrew, marmoset, and rhesus macaque) can shorten in the axial dimension in response to myopic defocus. METHODS. Chicks wore positive or negative lenses over one eye for 3 days. Tree shrews were measured during recovery from induced myopia after 5 days of monocular deprivation for 1 to 9 days. Marmosets were measured during recovery from induced myopia after monocular deprivation, or wearing negative lenses over one or both eyes, or from wearing positive lenses over one or both eyes. Rhesus macaques were measured after recovery from induced myopia after monocular deprivation, or wearing negative lenses over one or both eyes. Axial length was measured with ultrasound biometry in all species. RESULTS. Tree shrew eyes showed a strong trend to shorten axially to compensate for myopic defocus. Of 34 eyes that recovered from deprivation-induced myopia for various durations, 30 eyes (88%) shortened, whereas only 7 fellow eyes shortened. In chicks, eyes wearing positive lenses reduced their rate of ocular elongation by two-thirds, including 38.5% of eyes in which the axial length became shorter than before. Evidence of axial shortening in rhesus macaque (40%) and marmoset (6%) eyes also occurred when exposed to myopic defocus, although much less frequently than that in eyes of tree shrews. The axial shortening was caused mostly by the reduction in vitreous chamber depth. CONCLUSIONS. Eyes of chick, tree shrew, marmoset, and rhesus macaque can shorten axially when presented with myopic defocus, whether the myopic defocus is created by wearing positive lenses, or is the result of axial elongation of the eye produced by prior negative lens wear or deprivation. This eye shortening facilitates compensation for the imposed myopia. Implications for human myopia control are significant

IMI - Myopia Control Reports Overview and Introduction

With the growing prevalence of myopia, already at epidemic levels in some countries, there is an urgent need for new management approaches. However, with the increasing number of research publications on the topic of myopia control, there is also a clear necessity for agreement and guidance on key issues, including on how myopia should be defined and how interventions, validated by well-conducted clinical trials, should be appropriately and ethically applied. The International Myopia Institute (IMI) reports the critical review and synthesis of the research evidence to date, from animal models, genetics, clinical studies, and randomized controlled trials, by more than 85 multidisciplinary experts in the field, as the basis for the recommendations contained therein. As background to the need for myopia control, the risk factors for myopia onset and progression are reviewed. The seven generated reports are summarized: (1) Defining and Classifying Myopia, (2) Experimental Models of Emmetropization and Myopia, (3) Myopia Genetics, (4) Interventions for Myopia Onset and Progression, (5) Clinical Myopia Control Trials and Instrumentation, (6) Industry Guidelines and Ethical Considerations for Myopia Control, and (7) Clinical Myopia Management Guidelines

HIF-driven SF3B1 induces KHK-C to enforce fructolysis and heart disease.

Fructose is a major component of dietary sugar and its overconsumption exacerbates key pathological features of metabolic syndrome. The central fructose-metabolising enzyme is ketohexokinase (KHK), which exists in two isoforms: KHK-A and KHK-C, generated through mutually exclusive alternative splicing of KHK pre-mRNAs. KHK-C displays superior affinity for fructose compared with KHK-A and is produced primarily in the liver, thus restricting fructose metabolism almost exclusively to this organ. Here we show that myocardial hypoxia actuates fructose metabolism in human and mouse models of pathological cardiac hypertrophy through hypoxia-inducible factor 1α (HIF1α) activation of SF3B1 and SF3B1-mediated splice switching of KHK-A to KHK-C. Heart-specific depletion of SF3B1 or genetic ablation of Khk, but not Khk-A alone, in mice, suppresses pathological stress-induced fructose metabolism, growth and contractile dysfunction, thus defining signalling components and molecular underpinnings of a fructose metabolism regulatory system crucial for pathological growth