What is it like to be a rat? Rat sensory perception and its implications for experimental design and rat welfare

This review of rat sensory perception spans eight decades of work conducted across diverse research fields. It covers rat vision, audition, olfaction, gustation, and somatosensation, and describes how rat perception differs from and coincides with ours. As Nagel's seminal work (1974) implies, we cannot truly know what it is like to be a rat, but we can identify and acknowledge their perceptual biases. These primarily nocturnal rodents are extremely sensitive to light, with artificial lighting frequently causing retinal degeneration, and their vision extends into the ultraviolet. Their olfactory sensitivity and ultrasonic hearing means they are influenced by environmental factors and conspecific signals that we cannot perceive. Rat and human gustation are similar, being opportunistic omnivores, yet this sense becomes largely redundant in the laboratory, where rodents typically consume a single homogenous diet. Rat somatosensation differs from ours in their thigmotactic tendencies and highly sensitive, specialised vibrissae. Knowledge of species-specific perceptual abilities can enhance experimental designs, target resources, and improve animal welfare. Furthermore, the sensory environment has influences from neurone to behaviour, so it can not only affect the senses directly, but also behaviour, health, physiology, and neurophysiology. Research shows that environmental enrichment is necessary for normal visual, auditory, and somatosensory development. Laboratory rats are not quite the simple, convenient models they are sometimes taken for; although very adaptable, they are complex mammals existing in an environment they are not evolutionarily adapted for. Here, many important implications of rat perception are highlighted, and suggestions are made for refining experiments and housing.     

Vision Training Methods for Sports Concussion Mitigation and Management

There is emerging evidence supporting the use vision training, including light board training tools, as a concussion baseline and neuro-diagnostic tool and potentially as a supportive component to concussion prevention strategies. This paper is focused on providing detailed methods for select vision training tools and reporting normative data for comparison when vision training is a part of a sports management program. The overall program includes standard vision training methods including tachistoscope, Brock’s string, and strobe glasses, as well as specialized light board training algorithms. Stereopsis is measured as a means to monitor vision training affects. In addition, quantitative results for vision training methods as well as baseline and post-testing *A and Reaction Test measures with progressive scores are reported. Collegiate athletes consistently improve after six weeks of training in their stereopsis, *A and Reaction Test scores. When vision training is initiated as a team wide exercise, the incidence of concussion decreases in players who participate in training compared to players who do not receive the vision training. Vision training produces functional and performance changes that, when monitored, can be used to assess the success of the vision training and can be initiated as part of a sports medical intervention for concussion prevention.     

Variations in length of stay of inpatients with COVID-19: A nationwide test of the new model of care under vision 2030 in Saudi Arabia

ObjectiveThe coronavirus disease 2019 (COVID-19) has impacted the Kingdom of Saudi Arabia (KSA) as it has other nations. However, length of stay (LOS), as a healthcare quality indicator, has not been examined across the healthcare regions in the KSA. Therefore, this study aimed to examine factors associated with LOS to better understand the Saudi Health System's performance in response to the COVID-19 pandemic in the newly suggested five Saudi regional business units (BUs).MethodsA retrospective study was conducted using Ministry of Health (MOH) data on hospital LOS during the period from March to mid-July 2020. Participants were adult inpatients (18 years or older) with confirmed COVID-19 (n = 1743 patients). The 13 regions of the KSA were united into the defined five regional BUs during the reorganization of the health system. Covariates included demographics such as age and sex, comorbidities, and complications of COVID-19. A multiple linear regression with stepwise forward selection was used to model LOS for other explanatory variables associated with LOS, including demographic, comorbidities, and complications.ResultsThe mean LOS was 11.85 days which differed significantly across the BUs, ranging from 9.3 days to 13.3 days (p value < 0.001). BUs differed significantly in LOS for transferred patients but not for patients in the intensive care unit (ICU) or those who died in-hospital. The multiple regression analysis revealed that the LOS for inpatients admitted in the Eastern and Southern BUs was significantly shorter than for those in the Central BU. (p value < 0.001). Admission to the ICU was associated with lengthier stays (p value < 0.0001). Factors significantly associated with shorter stays (compared to the reference), were being Saudi, death during admission, and patients referred to another hospital (p value < 0.05).ConclusionThe LOS for patients with COVID-19 differed across the proposed regional healthcare BUs, suggesting regional differences in quality of care under the reorganization of the national health system. Since patient and disease characteristics did not explain these findings, differences in staffing and other resources need to be examined to develop interventions.     

The isolation of stable cattle rod outer segments with an intact plasma membrane

A procedure is described to purify and stabilize cattle rod outer segments with an intact plasma membrane. Three criteria are applied to assess the integrity of the latter.Upon photolysis in these rod outer segments: (1) exogenous ATP cannot phosphorylate rhodopsin located in the disk membrane. (2) Endogenous cofactors (NADPH, NADPH-regenerating system) are still available in the rod cytosol and consequently retinol is the final photoproduct of photolysis of rhodopsin. (3) The rod cytosol can maintain a pH different from that of the medium, since the later stages of rhodopsin photolysis are independent of the medium pH.The stability and homogeneity of the preparation appear to be much better than those of freshly isolated frog rod outer segments, which have been used most frequently so far for experiments on the physiology of rod outer segments. In addition, these cattle rod outer segments remain intact during various manipulations and therefore considerably extend the experimental possibilities when intact rod outer segments are required.     

Translocation of the Drosophila transient receptor potential-like (TRPL) channel requires both the N- and C-terminal regions together with sustained Ca2+ entry

In Drosophila photoreceptors the transient receptor potential-like (TRPL), but not the TRP channels undergo light-dependent translocation between the rhabdomere and cell body. Here we studied which of the TRPL channel segments are essential for translocation and why the TRP channels are required for inducing TRPL translocation. We generated transgenic flies expressing chimeric TRP and TRPL proteins that formed functional light-activated channels. Translocation was induced only in chimera containing both the N- and C-terminal segments of TRPL. Using an inactive trp mutation and overexpressing the Na(+)/Ca(2+) exchanger revealed that the essential function of the TRP channels in TRPL translocation is to enhance Ca(2+)-influx. These results indicate that motifs present at both the N and C termini as well as sustained Ca(2+) entry are required for proper channel translocation.     

Thermal properties of rhodopsin: insight into the molecular mechanism of dim-light vision

Rhodopsin has developed mechanisms to optimize its sensitivity to light by suppressing dark noise and enhancing quantum yield. We propose that an intramolecular hydrogen-bonding network formed by ～20 water molecules, the hydrophilic residues, and peptide backbones in the transmembrane region is essential to restrain thermal isomerization, the source of dark noise. We studied the thermal stability of rhodopsin at 55 °C with single point mutations (E181Q and S186A) that perturb the hydrogen-bonding network at the active site. We found that the rate of thermal isomerization increased by 1-2 orders of magnitude in the mutants. Our results illustrate the importance of the intact hydrogen-bonding network for dim-light detection, revealing the functional roles of water molecules in rhodopsin. We also show that thermal isomerization of 11-cis-retinal in solution can be catalyzed by wild-type opsin and that this catalytic property is not affected by the mutations. We characterize the catalytic effect and propose that it is due to steric interactions in the retinal-binding site and increases quantum yield by predetermining the trajectory of photoisomerization. Thus, our studies reveal a balancing act between dark noise and quantum yield, which have opposite effects on the thermal isomerization rate. The acquisition of the hydrogen-bonding network and the tuning of the steric interactions at the retinal-binding site are two important factors in the development of dim-light vision.     

Zinc-binding Domain-dependent,Deaminase-independent Actions of Apolipoprotein B mRNA-editing Enzyme,Catalytic Polypeptide 2 (Apobec2), Mediate Its Effect on Zebrafish Retina Regeneration

The Apobec/AID family of cytosine deaminases can deaminate cytosine and thereby contribute to adaptive and innate immunity, DNA demethylation, and the modification of cellular mRNAs. Unique among this family is Apobec2, whose enzymatic activity has been questioned and whose function remains poorly explored. We recently reported that zebrafish Apobec2a and Apobec2b (Apobec2a,2b) regulate retina regeneration; however, their mechanism of action remained unknown. Here we show that although Apobec2a,2b lack cytosine deaminase activity, they require a conserved zinc-binding domain to stimulate retina regeneration. Interestingly, we found that human APOBEC2 is able to functionally substitute for Apobec2a,2b during retina regeneration. By identifying Apobec2-interacting proteins, including ubiquitin-conjugating enzyme 9 (Ubc9); topoisomerase I-binding, arginine/serine-rich, E3 ubiquitin protein ligase (Toporsa); and POU class 6 homeobox 2 (Pou6f2), we uncovered that sumoylation regulates Apobec2 subcellular localization and that nuclear Apobec2 controls Pou6f2 binding to DNA. Importantly, mutations in the zinc-binding domain of Apobec2 diminished its ability to stimulate Pou6f2 binding to DNA, and knockdown of Ubc9 or Pou6f2 suppressed retina regeneration.     

Comparative morphological analysis of compound eye miniaturization in minute hymenoptera

Due to their small size, diminutive parasitic wasps are outstanding subjects for investigating aspects of body miniaturization. Information on minute compound eyes is still scarce, and we therefore investigated eye morphology in one of the smallest known hymenopteran species Megaphragma mymaripenne (body size 0.2 mm) relative to Anaphes flavipes (body size 0.45 mm) and compared the data with available information for Trichogramma evanescens (body size 0.4 mm). The eyes of all three species are of the apposition kind, and each ommatidium possesses the typical cellular organization of ommatidia found in larger hymenopterans. Compound eye miniaturization does not therefore involve a reduction in cell numbers or elimination of cell types. Six size-related adaptations were detected in the smallest eyes investigated, namely a) a decrease in the radius of curvature of the cornea compared with larger hymenopterans; b) the lack of extensions to the basal matrix from secondary pigment cells; c) the interlocking arrangement of the retinula cell nuclei in neighboring ommatidia; d) the distal positions of retinula cell nuclei in M. mymaripenne; e) the elongated shape of retinula cell pigment granules of both studied species; and f) an increase in rhabdom diameter in M. mymaripenne compared with A. flavipes and T. evanescens. The adaptations are discussed with respect to compound eye miniaturizations as well as their functional consequences based on optical calculations.     

Integrating microscopy,art, and humanities to power STEAM learning in biology

Close observation is central to both art and science as practitioners in both disciplines describe, compare, and seek to understand or interpret the natural world. Indeed, as the artist and writer Guy Davenport noted, “The vision by which we discover the hidden in nature is sometimes called science, sometimes called art.” In the last decade, the movement to integrate science, technology, engineering, and mathematics with arts and humanities (i.e., STEAM learning) has gained traction in K–12 education. A recent National Academies report (2018) examines the case for integrating humanities and the arts in undergraduate STEM education. Microscopy provides an excellent vehicle for engaging all kinds of students in integrative (STEAM) learning about biology and for encouraging them to observe the world closely. In this essay adapted from my keynote address to the American Microscopical Society in 2020, I highlight activities and approaches that use microscopy to engage learners of all kinds, examine how using microscopes changes students’ attitudes about science and biology, and explore the intersection of microscopy and visual art.     

不同泪道硅胶引流管留置时间对慢性泪囊炎患者视力、生活质量及复发率的影响

目的:探讨不同泪道硅胶引流管留置时间对慢性泪囊炎患者的生活质量、视力及复发率的影响。方法:回顾性选取2018年1月2019年12月期间于我院就诊的慢性泪囊炎患者91例(128眼),根据术后泪道硅胶引流管留置时间分为A、B两组,其中A组泪道硅胶引流管留置时间6周,44例(61眼),B组泪道硅胶引流管留置时间12周,47例(67眼)。对比两组疗效、视力、并发症发生率、主诉溢泪发生率、生活质量及复发率。结果:A组拔管当天的总有效率高于B组(P<0.05),两组拔管后3个月总有效率对比无明显差异(P>0.05)。拔管后6个月两组社会功能、躯体疼痛、精神健康、生理功能、精力、情感职能、生理职能、总体健康维度评分均较术前升高(P<0.05),但两组组间对比未见统计学差异(P>0.05)。两组患者术前、拔管后3个月视力组间及组内比较均未见统计学差异(P>0.05)。两组患者主诉溢泪发生率比较未见统计学差异(P>0.05)。A组并发症发生率、复发率低于B组(P<0.05)。结论:泪道硅胶引流管留置时间的长短对慢性泪囊炎患者疗效、视力、生活质量、主诉溢泪发生率无明显影响,但留置6周者并发症发生率、复发率低于留置12周者,提示临床应视患者具体情况尽量缩短泪道硅胶引流管留置时间。