Structured illumination microscopy of a living cell

Due to diffraction, the resolution of imaging emitted light in a fluorescence microscope is limited to about 200 nm in the lateral direction. Resolution improvement by a factor of two can be achieved using structured illumination, where a fine grating is projected onto the sample, and the final image is reconstructed from a set of images taken at different grating positions. Here we demonstrate that with the help of a spatial light modulator, this technique can be used for imaging slowly moving structures in living cells. This article has been submitted as a contribution to the Festschrift entitled “Uncovering cellular sub-structures by light microscopy” in honour of Professor Cremer’s 65th birthday.     

Dynamic imaging of zebrafish heart with multi-planar light sheet microscopy

Light sheet fluorescence microscopy has become a research hotspot in biomedicine because of low phototoxicity, high speed, and high resolution. However, the conventional methods to acquire three-dimensional spatial information are mainly based on scanning, which inevitably increases photodamage and is not real-time. Here, we propose a method to generate controllable multi-planar illumination with a dielectric isosceles triangular array and a design of multi-planar light sheet fluorescence microscopy system. We carry out experiments of three-dimensional illumination beam measurement, volumetric imaging of fluorescent microspheres, and dynamic in vivo imaging of zebrafish heart to evaluate the performance of this system. In addition, we apply this system to study the effects of bisphenol fluorene on the heart shape and heart-beating rate of zebrafish. Our experiment results indicate that the multi-planar light sheet microscopy system provides a novel and feasible method for three-dimensional selected plane imaging and low-phototoxicity in vivo imaging.     

Effect of continuous illumination of varying length on the reproductive rhythms in rats; after‐effects

Abstract

Permanent oestrus was induced in 24, 61 and 100% of 2‐months old Wistar rats under conditions of continuous light exposure (LL) for 1, 2 and 6 months, respectively. After cessation of 2 months LL, rhythmic fluctuations of oestrus activity were observed.

The weight of newborns produced by females under LL during pregnancy was increased by 7% as compared to controls (P < 0.05). LL before mating did not affect embryonic development.

20‐day old pups produced by females which were kept in LL for 1, 2 months and more were significantly heavier than controls by 5, 18 and 30%, respectively.

The stimulatory effect of LL for 1 and 2 months on pre‐ and postnatal development was maintained in the subsequent reproduction cycle, when these females were transferred to normal conditions of LD 14:10.     

Eating Disorder or Disordered Eating? Non‐normative Eating Patterns in Obese Individuals

Binge eating disorder (BED) and night eating syndrome (NES) are putative eating disorders frequently seen in obese individuals. Data suggest that BED fulfills criteria for a mental disorder. Criteria for NES are evolving but at present do not require distress or functional impairment. It remains unclear whether BED and NES, as they are currently defined, are optimally useful for characterizing distinct patient subgroups. We propose that a distinction be made between “eating disorders” and “non‐normative” eating patterns without associated distress or impairment. Although non‐normative eating patterns may not be considered mental disorders, they may be very important in terms of their impact on body weight and health. More precise behavioral and metabolic characterization of subgroups with eating disorders and non‐normative eating behaviors has important implications for understanding the etiology, pathophysiology, and treatment of obesity. Ultimately, better understanding of the many pathways to increased energy intake may lead to targeted strategies for prevention of overweight and obesity in at‐risk individuals and populations.     

Dysregulation of Cav1.4 channels disrupts the maturation of photoreceptor synaptic ribbons in congenital stationary night blindness type 2

Mutations in the gene encoding Ca_v1.4, CACNA1F_, are associated with visual disorders including X-linked incomplete congenital stationary night blindness type 2 (CSNB2). In mice lacking Ca_v1.4 channels, there are defects in the development of “ribbon” synapses formed between photoreceptors (PRs) and second-order neurons. However, many CSNB2 mutations disrupt the function rather than expression of Ca_v1.4 channels. Whether defects in PR synapse development due to altered Ca_v1.4 function are common features contributing to the pathogenesis of CSNB2 is unknown. To resolve this issue, we profiled changes in the subcellular distribution of Ca_v1.4 channels and synapse morphology during development in wild-type (WT) mice and mouse models of CSNB2. Using Ca_v1.4-selective antibodies, we found that Ca_v1.4 channels associate with ribbon precursors early in development and are concentrated at both rod and cone PR synapses in the mature retina. In mouse models of CSNB2 in which the voltage-dependence of Ca_v1.4 activation is either enhanced (Ca_v1.4_I756T) or inhibited (CaBP4 KO), the initial stages of PR synaptic ribbon formation are largely unaffected. However, after postnatal day 13, many PR ribbons retain the immature morphology. This synaptic abnormality corresponds in severity to the defect in synaptic transmission in the adult mutant mice, suggesting that lack of sufficient mature synapses contributes to vision impairment in Ca_v1.4_I756T and CaBP4 KO mice. Our results demonstrate the importance of proper Ca_v1.4 function for efficient PR synapse maturation, and that dysregulation of Ca_v1.4 channels in CSNB2 may have synaptopathic consequences.     

The ecological impacts of nighttime light pollution: a mechanistic appraisal

The ecological impacts of nighttime light pollution have been a longstanding source of concern, accentuated by realized and projected growth in electrical lighting. As human communities and lighting technologies develop, artificial light increasingly modifies natural light regimes by encroaching on dark refuges in space, in time, and across wavelengths. A wide variety of ecological implications of artificial light have been identified. However, the primary research to date is largely focused on the disruptive influence of nighttime light on higher vertebrates, and while comprehensive reviews have been compiled along taxonomic lines and within specific research domains, the subject is in need of synthesis within a common mechanistic framework. Here we propose such a framework that focuses on the cross‐factoring of the ways in which artificial lighting alters natural light regimes (spatially, temporally, and spectrally), and the ways in which light influences biological systems, particularly the distinction between light as a resource and light as an information source. We review the evidence for each of the combinations of this cross‐factoring. As artificial lighting alters natural patterns of light in space, time and across wavelengths, natural patterns of resource use and information flows may be disrupted, with downstream effects to the structure and function of ecosystems. This review highlights: (i) the potential influence of nighttime lighting at all levels of biological organisation (from cell to ecosystem); (ii) the significant impact that even low levels of nighttime light pollution can have; and (iii) the existence of major research gaps, particularly in terms of the impacts of light at population and ecosystem levels, identification of intensity thresholds, and the spatial extent of impacts in the vicinity of artificial lights.     

Karyotypic evolution in Aotus

Great karyotypic diversity exists within the platyrrhine genus Aotus. Primarily by comparing banded karyograms of different forms of Aotus, the pattern of karyotypic evolution can be assessed. Out-group comparisons are used to establish primitive and derived states of particular chromosomes, and a parsimonious cladogram is constructed. Other karyotypic changes are then positioned at appropriate nodes of the cladogram. The resulting phylogenetic hypothesis is entirely self-consistent, is in accord with out-group comparisons, does not invoke hybridization between ancestral forms, and, importantly, indicates a single origin for each rearrangement of euchromatic segments. Moreover, it is consistent with the hypothesis, derived from pelage studies, that the more southerly Aotus taxa constitute a holophyletic group. The reconstructed ancestral karyotype had a diploid number of 54. There has been little loss of euchromatic material during Aotus evolution.