Two are better than one: Unraveling the functions of cone arrestin in zebrafish (Commentary on Renninger, Gesemann and Neuhauss)

Since the surprising discovery of a second visual arrestin in mammalian pinealocytes and cone photoreceptors, numerous studies have examined cone arrestin's structural and functional similarities to and differences from rod arrestin (Craft et al., 1994; Nikonov et al., 2008). The rod arrestin or Arrestin1 binds to and terminates the light-activated, phosphorylated G-protein-coupled rhodopsin (Xu et al., 1997), whereas both visual arrestins work in concert in cone photoreceptors to shut off the light-activated photoreceptor signal transduction cascade, as shown for mouse Sand M-opsin (Nikonov et al., 2008). In this issue of EJN, Renninger and colleagues add a new dimension to understanding the visual arrestin saga by introducing two rod arrestins (arrS), three b-arrestins, and focusing on two paralogs of cone arrestin (arr3a and arr3b) in the zebrafish (Danio rerio). The Arr3a is exclusively expressed in M- and L-wavelength sensitive cones, whereas Arr3b is found in S- and UV-wavelength-sensitive cones. Their comprehensive study provides the first clear evidence of Arr3a's involvement in the high temporal contrast sensitivity of cone vision. As zebrafish exhibit light responses after 3 days of development, they are an ideal animal to study visual behavior (Brockerhoff et al., 1995). They are tetrachromatic with ultraviolet-sensitive cones as well as red-, green- and blue-sensitive cones, and their retinas continue to grow throughout their life. Using this cone-dominated visual system as a model system for their analysis, Renninger et al. (2011) examined the cellular expression of the distinct isoforms of arrestin in the visual system using a combination of in-situ hybridization and cone arrestin paralog-specific antibodies to examine cellular distribution at different developmental stages. These straightforward morphological experiments were followed by a set of elegant physiological experiments using targeted gene knockdown of the two cone arrestins in zebrafish larvae to unravel their visual responses with electroretinography. The functional knockdown of arr3a led to an electroretinography photo-response recovery delay. Additional experiments with the functional inactivation of arr3a were used to dissect out the psychophysical responses with optokinetics, a stereotypic ocular movement that is probably mediated by the modulation of M- and L-cone input (Orger & Baier, 2005). These latter experiments distinguished behavioral differences between low-contrast (dark-adapted) conditions that affected high temporal frequency patterns, and high-contrast (lightadapted) conditions that showed a deceleration of the temporal transfer function in the arr3a morphant larvae. Because of the lower abundance of the S- and UV-wavelength-sensitive cones in zebrafish, the function of arr3b remains undetermined; however, this work provides conclusive evidence that arr3a regulates high temporal resolution in high acuity color vision with experiments that are not possible in the rod-dominant mammalian retina. This work illustrates the use of the zebrafish as a vertebrate model to address the basic cellular function of cone arrestin and contributes to our broader understanding of visual processing and the complex physiology of high acuity color vision

Optimization of Application Timing and Frequency of Microbial Inoculants for Turfgrass Disease Control

NYS IPM Type: Project ReportConsiderable information is now available concerning the use of microbial inoculants for the control of turfgrass diseases. However, despite positive experimental results, few microbial inoculants have been highly effective in field studies or in commercial use on golf courses. A number of studies have shown that microbial agents perform most effectively when populations can be maintained at high levels, usually at populations exceeding 107 cells/g soil. However, applications made during the daytime hours may limit population development due to UV exposure or to desiccation. The limited number of success stories of biological control on golf courses have been from sites where applications of biological control organisms were applied during the overnight hours. Technology is now available for golf course superintendents to culture microbial inoculants on site at the golf course and apply inoculants directly through the irrigation system at any time of the day or night. It is now feasible for superintendents to make applications on a daily basis. This study was designed to evaluate the impacts of application scheduling on the disease control efficacy of introduced microbial inoculants

Retinal Neovascular Disorders: Mouse Models for Drug Development Studies

Neovascularization is a hallmark of several eye diseases leading to visual impairment, and its epidemiological impact is substantial (Lee et al. 1998). In retinal degenerative disease models, neovascularization is the process by which the choroid and/or retina become infiltrated with new blood vessels. In retinal neovascularization (RNV), sprouting retinal vessels penetrate the inner limiting membrane (ILM) and grow into the vitreous, and in some cases, grow through the avascular outer retina into the subretinal space (Campochiaro 2000). Numerous clinical and ­experimental observations indicate that ischemia (or hypoxia) is the driving force behind RNV (Michaelson and Steedman 1949). Occlusion of retinal vessels leading to ischemia is a feature of diseases with RNV, including diabetic retinopathy (DR) and retinopathy of prematurity (ROP) (Campochiaro 2000)

Photoreceptors of Nrl −/− Mice Coexpress Functional S- and M-cone Opsins Having Distinct Inactivation Mechanisms

The retinas of mice null for the neural retina leucine zipper transcription factor (Nrl −/−) contain no rods but are populated instead with photoreceptors that on ultrastructural, histochemical, and molecular criteria appear cone like. To characterize these photoreceptors functionally, responses of single photoreceptors of Nrl −/− mice were recorded with suction pipettes at 35–37°C and compared with the responses of rods of WT mice. Recordings were made either in the conventional manner, with the outer segment (OS) drawn into the pipette (“OS in”), or in a novel configuration with a portion of the inner segment drawn in (“OS out”). Nrl −/− photoreceptor responses recorded in the OS-out configuration were much faster than those of WT rods: for dim-flash responses tpeak = 91 ms vs. 215 ms; for saturating flashes, dominant recovery time constants, τD = 110 ms vs. 240 ms, respectively. Nrl −/− photoreceptors in the OS-in configuration had reduced amplification, sensitivity, and slowed recovery kinetics, but the recording configuration had no effect on rod response properties, suggesting Nrl −/− outer segments to be more susceptible to damage. Functional coexpression of two cone pigments in a single mammalian photoreceptor was established for the first time; the responses of every Nrl −/− cell were driven by both the short-wave (S, λmax ≈ 360 nm) and the mid-wave (M, λmax ≈ 510 nm) mouse cone pigment; the apparent ratio of coexpressed M-pigment varied from 1:1 to 1:3,000 in a manner reflecting a dorso-ventral retinal position gradient. The role of the G-protein receptor kinase Grk1 in cone pigment inactivation was investigated in recordings from Nrl −/−/Grk1−/− photoreceptors. Dim-flash responses of cells driven by either the S- or the M-cone pigment were slowed 2.8-fold and 7.5-fold, respectively, in the absence of Grk1; the inactivation of the M-pigment response was much more seriously retarded. Thus, Grk1 is essential to normal inactivation of both S- and M-mouse cone opsins, but S-opsin has access to a relatively effective, Grk1-independent inactivation pathway

A Defective Crosstalk Between Neurons and Müller Glial Cells in the rd1 Retina Impairs the Regenerative Potential of Glial Stem Cells

Müller glial cells (MGC) are stem cells in the retina. Although their regenerative capacity is very low in mammals, the use of MGC as stem cells to regenerate photoreceptors (PHRs) during retina degenerations, such as in retinitis pigmentosa, is being intensely studied. Changes affecting PHRs in diseased retinas have been thoroughly investigated; however, whether MGC are also affected is still unclear. We here investigated whether MGC in retinal degeneration 1 (rd1) mouse, an animal model of retinitis pigmentosa, have impaired stem cell properties or structure. rd1 MGC showed an altered morphology, both in culture and in the whole retina. Using mixed neuron-glial cultures obtained from newborn mice retinas, we determined that proliferation was significantly lower in rd1 than in wild type (wt) MGC. Levels of stem cell markers, such as Nestin and Sox2, were also markedly reduced in rd1 MGC compared to wt MGC in neuron-glial cultures and in retina cryosections, even before the onset of PHR degeneration. We then investigated whether neuron-glial crosstalk was involved in these changes. Noteworthy, Nestin expression was restored in rd1 MGC in co-culture with wt neurons. Conversely, Nestin expression decreased in wt MGC in co-culture with rd1 neurons, as occurred in rd1 MGC in rd1 neuron-glial mixed cultures. These results imply that MGC proliferation and stem cell markers are reduced in rd1 retinas and might be restored by their interaction with "healthy" PHRs, suggesting that alterations in rd1 PHRs lead to a disruption in neuron-glial crosstalk affecting the regenerative potential of MGC.Fil: Volonté, Yanel Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Vallese Maurizi, Harmonie Agostina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Dibo, Marcos Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Ayala Peña, Victoria Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Garelli, Andres. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Zanetti, Samanta Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Turpaud Barrera, Axel Hector Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Craft, Cheryl Mae. University Of Southern California; Estados UnidosFil: Rotstein, Nora Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Politi, Luis Enrique. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: German, Olga Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentin

Responding to Natural and industrial Disasters: Partnerships and Lessons Learned

OBJECTIVES: The aim of this study was to provide insights learned from disaster research response (DR2) efforts following Hurricane Harvey in 2017 to launch DR2 activities following the Intercontinental Terminals Company (ITC) fire in Deer Park, Texas, in 2019. METHODS: A multidisciplinary group of academic, community, and government partners launched a myriad of DR2 activities. RESULTS: The DR2 response to Hurricane Harvey focused on enhancing environmental health literacy around clean-up efforts, measuring environmental contaminants in soil and water in impacted neighborhoods, and launching studies to evaluate the health impact of the disaster. The lessons learned after Harvey enabled rapid DR2 activities following the ITC fire, including air monitoring and administering surveys and in-depth interviews with affected residents. CONCLUSIONS: Embedding DR2 activities at academic institutions can enable rapid deployment of lessons learned from one disaster to enhance the response to subsequent disasters, even when those disasters are different. Our experience demonstrates the importance of academic institutions working with governmental and community partners to support timely disaster response efforts. Efforts enabled by such experience include providing health and safety training and consistent and reliable messaging, collecting time-sensitive and critical data in the wake of the event, and launching research to understand health impacts and improve resiliency