Wnt Signaling in Form Deprivation Myopia of the Mice Retina

Background

The canonical Wnt signaling pathway plays important roles in cellular proliferation and differentiation, axonal outgrowth, cellular maintenance in retinas. Here we test the hypothesis that elements of the Wnt signaling pathway are involved in the regulation of eye growth and prevention of myopia, in the mouse form-deprivation myopia model.

Methodology/Principal Findings

(1) One hundred twenty-five C57BL/6 mice were randomly distributed into form-deprivation myopia and control groups. Form-deprivation myopia (FDM) was induced by suturing the right eyelid, while the control group received no treatment. After 1, 2, and 4 weeks of treatment, eyes were assessed in vivo by cycloplegic retinoscopic refraction and axial length measurement by photography or A-scan ultrasonography. Levels of retinal Wnt2b, Fzd5 and β-catenin mRNA and protein were evaluated using RT-PCR and western blotting, respectively. (2) Another 96 mice were divided into three groups: control, drugs-only, and drugs+FDM (by diffuser). Experimentally treated eyes in the last two groups received intravitreal injections of vehicle or the proteins, DKK-1 (Wnt-pathway antagonist) or Norrin (Wnt-pathway agonist), once every three days, for 4 injections total. Axial length and retinoscopic refraction were measured on the 14th day of form deprivation.Following form-deprivation for 1, 2, and 4 weeks, FDM eyes had a relatively myopic refractive error, compared with contralateral eyes. There were no significant differences in refractive error between right and left eye in control group. The amounts of Wnt2b, Fzd5 and β-catenin mRNA and protein were significantly greater in form-deprived myopia eyes than in control eyes.DKK-1 (antagonist) reduced the myopic shift in refractive error and increase in axial elongation, whereas Norrin had the opposite effect in FDM eyes.

Conclusions/Significance

Our studies provide the first evidence that the Wnt2b signaling pathway may play a role in the development and progression of form-deprivation myopia, in a mammalian model.     

Breed- and gender-dependent differences in eye growth and form deprivation responses in chick

This study investigated the influences of breed and gender on the response to form deprivation and subsequent changes (recovery) when normal vision was restored. Two breeds of chickens, the White Leghorn and broiler cross, were compared, as well as male and female chicks for the White Leghorn breed. Normal eye growth was faster in the more rapidly growing broiler chicks; gender-differences were not as great as breed-differences although male White Leghorns ultimately became heavier and showed slightly greater normal eye growth than females. While both breeds showed high myopia and axial elongation in response to form deprivation, they differed significantly in the magnitude of their response, with White Leghorns showing more myopia and greater axial elongation and also recovering more slowly. Responses to form deprivation were similar for both genders, with respect to both the amount of myopia and axial elongation produced, although the female chicks recovered faster. Together these observations indicate that, although the overall pattern of response of form deprivation is consistent across both breed and gender, related quantitative differences in responses can be expected and need to be taken into account in experimental design and cross-study comparisons.Abbreviations WL White Leghorn chicks - BC broiler cross chicks - M male chicks - F female chicks - N normal eye - T treated eye - FD form deprivation - ACD anterior chamber depth - ALT axial lens thickness - VCD vitreous chamber depth - AL axial length     

Assessment of the Association of Matrix Metalloproteinases with Myopia,Refractive Error and Ocular Biometric Measures in an Australian Cohort

Extracellular matrix proteins have been implicated in protein remodelling of the sclera in refractive error. The matrix metalloproteinases (MMPs) falling into the collagenase (MMP1, MMP8, MMP13), gelatinase (MMP2, MMP9) and stromelysin (MMP3, MMP10, MMP11) functional groups are particularly important. We wished to assess their association with myopia, refractive error and ocular biometric measures in an Australian cohort. A total of 543 unrelated individuals of Caucasian ethnicity were genotyped including 269 myopes (≤−1.0D) and 274 controls (>−1.0D). Tag single nucleotide polymorphisms (SNPs) (n = 53) were chosen to encompass these eight MMPs. Association tests were performed using linear and logistic regression analysis with age and gender as covariates. Spherical equivalent, myopia, axial length, anterior chamber depth and corneal curvature were the phenotypes of interest. Initial findings indicated that the best p values for each trait were 0.02 for myopia at rs2274755 (MMP9), 0.02 for SE at both rs3740938 (MMP8) and rs131451 (MMP11), 0.01 for axial length at rs11225395 (MMP8), 0.01 for anterior chamber depth at rs498186 (MMP1) and 0.02 at rs10488 (MMP1). However, following correction for multiple testing, none of these SNPs remained statistically significant. Our data suggests that the MMPs in the collagenase, gelatinase and stromelysin categories do not appear to be associated with myopia, refractive error or ocular biometric measures in this cohort.     

A detailed paraxial schematic eye for the White Leghorn chick

We studied the normal ocular development of the chick (Gallus gallus domesticus, White Leghorn) up to 15 days of age using both longitudinal and cross-sectional methods. The change in refractive error, corneal curvature and axial ocular distances were used to construct schematic eyes. Equations are presented which allow prediction of refractive error changes associated with changes in vitreous chamber depth. The mean refractive error was +3.2 D at hatching, which reduced by 66% over the first 3 days and stabilized by 11 days of age. The lens thickened and the anterior chamber deepened from hatching, but vitreal elongation and corneal flattening were delayed until after the first 3 days, suggesting that normal eye growth may be initially inhibited or inactive during an initial emmetropization period, and subsequently activated in response to myopic defocus arising from the continually expanding lens. Finally, when compared with published data on other chick strains, we find differences in the degree of hyperopia at hatching due to differences in lens thickness. However, the rate of ocular and vitreal expansion and the developmental changes in corneal power are similar, making the schematic eyes presented here generally applicable to different strains of chickens.     

Animal Models of Myopia: Learning How Vision Controls the Size of the Eye

As they grow up, approximately 25% of children in the United States become myopic (nearsighted). A much smaller fraction become significantly hyperopic (farsighted), while the majority develop little or no refractive error and are emmetropic. The causes of refractive error, especially myopia, have been the subject of debate for more than a century. Some have held that myopia is primarily an inherited disorder, and others, that myopia is caused by protracted near work and, especially, by accommodation during protracted near work. It has not been possible, based solely on clinical observations, to resolve the relative roles of heredity versus environment in the development of refractive error. In the mid-1970s, several animal models were developed to study the mechanisms underlying refractive error. Using animal models, it was found that the visual environment exerts a powerful influence on refractive state by controlling the axial length of the eye during the postnatal developmental period. Although several species have been examined, three have emerged as primary models and have played complementary roles: tree shrews (mammals closely related to primates), chicks, and monkeys. Each has advantages and disadvantages. Collectively, research on animal models has provided evidence on three issues, namely that (1) the visual environment can produce refractive error; (2) an emmetropization mechanism normally guides eyes to low refractive error; and (3) under-accommodation, rather than excessive accommodation, may cause myopia. Two decades of research on animal models have provided criteria that may be used to evaluate the usefulness of additional species as models of emmetropization.     

Effects of confined space and near vision stimulation on refractive status and vitreous chamber depth in adolescent rhesus monkeys

This study aimed to investigate the effects of sustained near vision stimulation, on the refractive development and elongation of the vitreous chamber in adolescent rhesus monkeys. A total of 12 adolescent rhesus monkeys (1.5–2.0 years old) were randomly assigned to 3 groups. In groups A (n=4) and B (n=4), monkeys were reared in close-vision cages for 8 and 4 h d⁻¹, respectively; tiny granules were added on the cage floor to avoid visual deprivation and to encourage near gaze. In group C (n=4), monkeys were reared in open-vision cages, with non-granule food as a control. Vitreous chamber depth, refractive status, and corneal refractive power were assessed over 18 months. Paired t-test was used to compare the differences and a P-value<0.05 was considered to be statistically significant. In group A, vitreous chamber depth and optical axis elongated significantly, and refractive error shifted towards myopia during the observation period. In group B, vitreous chambers and optical axis elongated but the refractive power did not show significant changes. In group C, there was no significant elongation in vitreous chambers and optical axis, and the refractive power changed slightly towards hypermetropia. There were no significant changes in corneal refractive power in each group. Sustained near vision can promote vitreous chamber growth and induce myopic shifts in refractive power in adolescent monkeys. Our results demonstrate the potential for a primate model of near-work-related myopia.     

Interocular Difference of Peripheral Refraction in Anisomyopic Eyes of Schoolchildren

Purpose

Refraction in the peripheral visual field is believed to play an important role in the development of myopia. The purpose of this study was to investigate the differences in peripheral refraction among anisomyopia, isomyopia, and isoemmetropia for schoolchildren.

Methods

Thirty-eight anisomyopic children were recruited and divided into two groups: (1) both eyes were myopic (anisomyopic group, AM group) and (2) one eye was myopic and the contralateral eye was emmetropic (emmetropic anisomyopic group, EAM group). As controls, 45 isomyopic and isoemmetropic children were also recruited with age and central spherical equivalent (SE) matched to those of the AM and EAM groups. The controls were divided into three groups: (1) intermediate myopia group (SE matched to the more myopic eye of AM group), (2) low myopia group (SE matched to the less myopic eye of AM group and the more myopic eye of EAM group), and (3) emmetropia group (SE matched to the less myopic eye of EAM group). Peripheral refraction at 7 points across the central ±30° on the horizontal visual field with a 10° interval was measured with an autorefractor. Axial length (AL), corneal curvature (CC), and anterior chamber depth (ACD) were also determined by using the Zeiss IOL-Master.

Results

The relative peripheral spherical equivalent [RPR(M)] and relative peripheral spherical value [RPR(S)] of the more myopic eye was shifted more hyperopically than the contralateral eye in both the AM and the EAM groups (both p<0.0001). The RPR(M, S) of the less myopic eyes in the AM and EAM groups showed a relatively flat trend across the visual field and were not significantly different from the emmetropia group. The RPR(M, S) of less myopic eyes in the AM group were shifted less hyperopically than in the isomyopic low myopia group and the more myopic eye of the EAM group [RPR(M), p = 0.007; RPR(S), p = 0.001], although the central SEs of the three groups were not significantly different from each other. However, RPR(M, S) of the more myopic eyes were not different from the corresponding isomyopic groups. There was also no significant difference in the relative peripheral astigmatism [RPR(J0, J45)] between the more and the less myopic eyes in either the AM or the EAM group.

Conclusion

Refraction of anisomyopia differs between the two eyes not only at the central visual field but also at the off-axis periphery. The relative peripheral refraction of the more myopic eye of anisomyopia was shifted hyperopically, as occurs in isomyopia with similar central subjective SE values. Less myopic eyes were much less hyperopically shifted in relative peripheral refraction than the corresponding isomyopic eyes, but are comparable to emmetropic eyes. This emmetropia-like relative peripheral refraction in less myopic eyes might be a factor responsible for slowing down the progression of myopia.     

The refractive development of the eye of the American kestrel (Falco sparverius): a new avian model

Summary Most measures of avian visual performance are carried out on commonly available domestic species such as the chicken, and most of the data on avian induced refractive error deals with chickens. Raptors are predatory birds in which good visual resolving ability is particularly important. Behavioral studies indicate that the eyes of raptors have two to three times the resolving ability of the human eye. The domestic chicken is precocial at hatching whereas most raptors are semi-altricial. This study was an effort to determine if the effect of early visual deprivation on the refractive development of the chicken eye can be reproduced in the American kestrel, a species which is not domesticated and in which the need for acute vision is particularly important.Visual deprivation was achieved by unilaterally applying translucent plastic goggles over the eyes of kestrels two days after hatching. Refractive error was measured using a retinoscope and trial lenses. Ocular growth was monitored by A-scan ultrasonography, and frozen ocular sections of sacrificed birds. The effect of the experimental manipulation on the contralateral control eye and body weight was evaluated each day over a 42-day period. The goggles did not significantly affect the normal changes in body weight or the normal pattern of ocular growth and refractive development in the untreated eyes. An analysis of the refractive state changes as a result of form deprivation was made each week for 6 weeks after hatching on both the treated and untreated eyes in a separate group of experimental birds. Visual form deprivation caused a significant myopic shift in refractive error and a significant increase in the vitreous chamber depth in the treated eyes at 3 and 6 weeks of age. However, the amount of myopia produced is much less than that induced in chicks, and in certain cases hyperopia is produced. The kestrels recover from myopia and hyperopia within 10 days of goggle removal, after 3 to 4 weeks of deprivation.This study is the first indication that chickens may not be a representative bird model for studying form deprivation myopia. First, myopia is not always produced in kestrels in response to form deprivation. Second, kestrels are severely myopic at hatching and therefore, the direction of emmetropization is opposite to that found in hatchling chicks.     

Ocular Axial Length and Its Associations in Chinese: The Beijing Eye Study

Purpose

To investigate the normative data of ocular axial length and its associations in Chinese.

Method

The population-based Beijing Eye Study 2011 is a cross-sectional study performed in Greater Beijing. The study included 3468 individuals (1963 (56.6%) women) with a mean age of 64.6±9.8 years (range: 50–93 years). A detailed ophthalmic and medical examination was performed. Axial length was measured by optical low-coherence reflectometry.

Results

Axial length measurements were available for 3159 (91.1%) study participants. Mean axial length was 23.25±1.14 mm (range: 18.96–30.88 mm). In multivariate analysis, axial length was significantly associated with the systemic parameters of higher age (P<0.001), higher body height (P = 0.003), higher level of education (P<0.001) and urban region of habitation (P<0.001), and with the ocular parameters of thicker central cornea (P = 0.001), higher corneal curvature radius (P<0.001), deeper anterior chamber (P<0.001), thicker lens (P<0.001), more myopic refractive error (P<0.001), larger pupil diameter (P = 0.018), and higher best corrected visual acuity (P<0.001). It was additionally and negatively associated with the lens vault (P<0.001). In highly myopic eyes, axial length was significantly associated with lower level of education (P = 0.008), more myopic refractive error (P<0.001), and lower best corrected visual acuity (P = 0.034).

Conclusions

Mean ocular axial length in the older adult population of Greater Beijing (23.25±1.14 mm) was similar to the value measured in other urban populations and was higher than in a rural Central Indian population. The association between axial length and older age may potentially be associated with a survival artifact. The association between axial length and body height agrees with the general association between anthropomorphic measures and eye globe size. The association with the level of education and urban region of habitation confirms with previous studies. In contrast in highly myopic eyes, axial length was negatively associated with educational level and best corrected visual acuity.     

Rapid,Accurate, and Non-Invasive Measurement of Zebrafish Axial Length and Other Eye Dimensions Using SD-OCT Allows Longitudinal Analysis of Myopia and Emmetropization

Refractive errors in vision can be caused by aberrant axial length of the eye, irregular corneal shape, or lens abnormalities. Causes of eye length overgrowth include multiple genetic loci, and visual parameters. We evaluate zebrafish as a potential animal model for studies of the genetic, cellular, and signaling basis of emmetropization and myopia. Axial length and other eye dimensions of zebrafish were measured using spectral domain-optical coherence tomography (SD-OCT). We used ocular lens and body metrics to normalize and compare eye size and relative refractive error (difference between observed retinal radial length and controls) in wild-type and lrp2 zebrafish. Zebrafish were dark-reared to assess effects of visual deprivation on eye size. Two relative measurements, ocular axial length to body length and axial length to lens diameter, were found to accurately normalize comparisons of eye sizes between different sized fish (R² = 0.9548, R² = 0.9921). Ray-traced focal lengths of wild-type zebrafish lenses were equal to their retinal radii, while lrp2 eyes had longer retinal radii than focal lengths. Both genetic mutation (lrp2) and environmental manipulation (dark-rearing) caused elongated eye axes. lrp2 mutants had relative refractive errors of −0.327 compared to wild-types, and dark-reared wild-type fish had relative refractive errors of −0.132 compared to light-reared siblings. Therefore, zebrafish eye anatomy (axial length, lens radius, retinal radius) can be rapidly and accurately measured by SD-OCT, facilitating longitudinal studies of regulated eye growth and emmetropization. Specifically, genes homologous to human myopia candidates may be modified, inactivated or overexpressed in zebrafish, and myopia-sensitizing conditions used to probe gene-environment interactions. Our studies provide foundation for such investigations into genetic contributions that control eye size and impact refractive errors.     

Genetic variation and evolution in the red cell carbonic anhydrase isozymes of macaque monkeys

The electrophoretic phenotypes of the two isozymes of red cell carbonic anhydrase, CA I and CA II, are described in nine species of macaque monkeys from southeast Asia and Japan. Twelve phenotypes of CA I, apparently under the control of seven alleles, and five phenotypes of CA II, under the control of three alleles, were found in the different macaque populations studied. Extensive electrophoretic polymorphisms of CA I were found in three species (Macaca nemestrina, Macaca speciosa, and Macaca fuscata), and polymorphisms at the CA II locus were found in Macaca irus, Macaca mulatta, and M. nemestrina. In addition to the electrophoretic polymorphisms at the CA I locus in M. nemestrina, an inherited deficiency of CA I was also discovered in which approximately 30% of the individuals in all populations of M. nemestrina tested showed the deficient phenotype. Although the recessive gene controlling this deficiency appears to be an allele of the CA I locus, it is postulated that the CA I deficiency could also be under the control of a closely linked gene. The comparative data on the extent of genetic variation observed in the two isozymes of red cell carbonic anhydrase in macaques appear to support the concept that CA I has evolved more rapidly than CA II in mammals.Supported by USPHS grant GM-15419 and NSF grants GF-253, GB-7426, and GB-15060 of the U.S.-Japan Cooperative Science and Systemic Biology Programs.     

Structural differentiation of microhabitats of sympatricmacaca fascicularis andM. nemestrina in East Kalimantan,Indonesia

Macaca nemestrina andM. fascicularis coexist through much of their geographic ranges in Southeast Asia, but locally they segregate into drier hilly terrain and wetter alluvial riverine terrain respectively. SinceM. fascicularis travel arboraally andM. nemestrina, travel terrestrially, structural characteristics of habitats on the two different substrates may explain local segregation of these two species. This paper reports measures comparing habitat structure ofM. fascicularis fascicularis andM. nemestrina nemestrina at the Mentoko site in East Kalimantan, Indonesia. Results show that (1) ground cover is thicker; (2) there are fewer gaps in the canopy; and (3) the foliage of the canopy is more dense in habitat occupied by arborealM. f. fascicularis than in habitat occupied byM. n. nemestrina. These differences in habitat structure appear to explain segregation of the two species at the Mentoko. Similar differences in habitat may permit coexistence of the two species throughout their geographical ranges.     

Defects of the Lamina Cribrosa in High Myopia and Glaucoma

Purpose

We evaluated the prevalence and characteristics of the defects of the lamina cribrosa (LC) in high myopia and glaucoma, and compared them with control eyes using swept-source optical coherence tomography (SS-OCT).

Methods

One hundred fifty-nine eyes of 108 participants were divided into four subgroups; high myopia with glaucoma (MG, 67 eyes of 46 subjects), glaucoma without high myopia (G, 22 eyes of 13 subjects), high myopia without glaucoma (M, 35 eyes of 29 subjects), and a control group with neither glaucoma nor high myopia (C, 35 eyes of 20 subjects). The LC defects were identified and located using a standardized protocol in serial horizontal OCT scans. The prevalence rates of the defects were compared among the groups. Demographic and ocular factors were compared between eyes with and without defects.

Results

LC defects were observed in one eye (0.03%) in the C group, 8 eyes (22.9%) in the M group, 11 eyes (50%) in the G group, and 28 eyes (41.8%) in the MG group. The prevalence rates of the defects differed significantly among the groups (P = 0.0009). Most eyes with defects in the G and MG groups (79.5%) had damage in the corresponding visual hemifields. Other factors such as visual acuity, intraocular pressure, axial length, refractive error, disc ovality, or parapapillary atrophy area did not differ significantly between eyes with and without LC defects.

Conclusions

High myopia and glaucoma significantly increased the risk of LC damage. The LC damage in non-glaucomatous highly myopic eyes may at least partly explain the increased risk of developing glaucoma in myopic eyes.     

Initial calcification of the upper permanent incisor in Japanese macaques

Fifteen laboratory-born Japanese macaques,Macaca fuscata (Blyth, 1875), were examined radiographically for the timing of initial crown calcification of the permanent upper first incisors. The mean age of initial calcification was 199.8 days in females and 204.7 days in males; the sexual difference was significant (p<.05). Precocious incisor calcification in females inM. fuscata resembles that inM. nemestrina andHomo sapiens.     

Glaucomatous-Type Optic Discs in High Myopia

Purpose

To assess the prevalence of glaucoma in patients with high myopia defined as myopic refractive error of >-8 diopters or axial length ≥26.5 mm.

Methods

The hospital-based observational study included 172 patients (336 eyes) with a mean age of 61.9±12.3 years and mean axial length of 30.1±2.3 mm (range: 24.7–39.1mm). Glaucomatous-type optic discs were defined by glaucomatous optic disc appearance. Glaucoma was defined by glaucomatous optic disc appearance and glaucomatous Goldmann visual field defects not corresponding with myopic macular changes.

Results

Larger disc area (mean: 3.18±1.94 mm²) was associated with longer axial length (P<0.001; standardized correlation coefficient: 0.45). Glaucoma was detected in 94 (28%; 95% Confidence intervals: 23%, 33%) eyes. In multivariate analysis, glaucoma prevalence was 3.2 times higher (P<0.001) in megalodiscs (>3.79 mm²) than in normal-sized discs or small discs (<1.51 mm²) after adjusting for older age. Axial length was not significantly (P = 0.38) associated with glaucoma prevalence in that model. Glaucoma prevalence increased by a factor of 1.39 for each increase in optic disc area by one mm². Again, axial length was not significantly (P = 0.38) associated with glaucoma prevalence when added to this multivariate model.

Conclusion

Within highly myopic individuals, glaucoma prevalence increased with larger optic disc size beyond a disc area of 3.8 mm². Highly myopic megalodiscs as compared to normal sized discs or small discs had a 3.2 times higher risk for glaucomatous optic nerve neuropathy. The increased glaucoma prevalence in axial high myopia was primarily associated with axial myopia associated disc enlargement and not with axial elongation itself.     

OCTA用于检测不同屈光人群的黄斑区视网膜密度和厚度及其相关性分析

目的:采用光学相干断层扫描血管成像技术(OCTA)检测不同屈光人群的黄斑区视网膜密度及厚度并分析其相关性。方法:选取2016年2月～2018年2月我院收治的近视患者200例为研究对象,根据等效球镜度数的差异将其分为轻度近视组(-0.50～-2.75D)52例、中度近视组(-3.00～-5.75D)46例、高度近视组(-6.00～-8.75D)48例、超高度近视组(≤-0.90D)54例。所有患者均进行OCTA检测,比较各组患者黄斑区不同区域视网膜血管密度以及厚度的差异。结果:轻度近视组、中度近视组、高度近视组、超高度近视组等效球镜均呈逐渐降低趋势,而眼轴长度均呈逐渐升高趋势,各组间对比差异有统计学意义(P0.05)。超高度近视组患者中心凹、中心凹旁、颞侧、上方、鼻侧、下方视网膜血管密度和中心凹、中心凹旁、颞侧、上方、鼻侧、下方视网膜厚度相比轻度近视组、中度近视组、高度近视组均显著降低(P0.05)。经Pearson相关性结果显示:近视屈光人群的黄斑中心凹以及上方视网膜血管密度以及视网膜厚度呈正相关关系(P0.05)。结论:采用OCTA检测不同屈光人群的黄斑区视网膜密度及厚度,结果表明近视屈光度患者的黄斑区视网膜密度增加以及黄斑区视网膜厚度的增厚呈正相关关系。     

530nm单色光诱导豚鼠近视眼模型的建立

目的应用530 nm单色光光照建立一种新型近视眼动物模型。方法20只约2周龄健康雄性豚鼠,随机分成两组（n=10）,实验组和对照组分别在绿光（530 nm）和白光（色温5000 k）下进行饲养。设置照明参数：光量子数相同,为每秒3×10-4μmol/cm2;实测光强度绿光为0.150 mW/cm2,白光为0.247 mW/cm2。实验前每组进行眼球生物学测量（屈光度、角膜曲率、眼轴各部分长度）,光照后12周重复测量以上数据,每只豚鼠均取右侧眼参数进行统计分析。结果光照前两组生物学测量参数差异无显著性。光照12周后,绿光组屈光度发生-3.125±0.76 D的变化,白光组为-1.075±0.71D,绿光组同对照白光组相比平均形成约2.0 D的近视,差异有显著性;绿光组眼轴和玻璃体腔分别增长0.98±0.13 mm与0.33±0.14 mm,对照组分别为0.77±0.22 mm与0.13±0.14 mm,绿光组较对照组眼轴和玻璃体腔长度延长较快,差异有显著性;光照后两组角膜曲率半径、前房深度和晶状体厚度均发生不同程度增加,但两组间变化差异无显著性。结论530 nm单色光诱导豚鼠眼球眼轴和玻璃体腔长度延长较快,产生近视.     

Amino acid compositions of the tryptic peptides comprising the beta-hemoglobin chain of Macaca nemestrina

The tryptic peptides comprising the aminoethylated β-hemoglobin chain of Macaca nemestrina were isolated by paper electrophoresis and chromatography. The results of stains for specific amino acids, comparison of peptide maps with those produced by aminoethlated β chains from human hemoglobin A, and amino acid analyses of all peptides in the macaque β chain support the conclusion that the primary structure of the β chain of M. nemestrina is identical to that of the corresponding chains of M. fuscata fuscata and M. fascicularis. The apparent evolutionary conservatism of macaque β chains is discussed in relation to the wide degree of structural variation previously observed among the α-hemoglobin chains of several species of Macaca.     

Macaque Pterygoid Muscles: Internal Architecture, Fiber length, and Cross-Sectional Area

Models of mastication require knowledge of fiber lengths and physiological cross-sectional area (PCS), a proxy for muscle force. I dissected 36 medial pterygoid and 36 lateral pterygoid muscles from 30 adult females of 3 macaque species (Macaca fascicularis, M. mulatta, M. nemestrina) using gross and chemical techniques and calculated PCS. These macaques have mechanically similar dietary niches and exhibit no significant difference in muscle architecture or fiber length. Fiber length does not scale with body size (mass) for either total pterygoid muscle or for medial pterygoid muscle mass. However, fiber length scales weakly with lateral pterygoid muscle mass. In each case, differences in PCS among species result from differences in muscle mass not fiber length. Medial pterygoid PCS scales isometrically with body size; larger animals have greater force production capabilities. Medial and lateral pterygoid PCS scale positively allometrically with facial size; individuals with more prognathic faces and taller mandibular corpora have greater PCS, and hence force, values. This positive allometry counters the less efficient positioning of masticatory muscles in longer-faced macaques. PCS is only weakly correlated with bone proxies previously used to estimate muscle force. Thus, predictions of muscle force from bone parameters will entail large margins of error and should be used with caution.     

The development of the refractive state in the newborn Thomson gazelle

Changes in refractive error during the first 3 months of life were studied retinoscopically in six Thomson gazelles (Gazella thomsoni). Animals were hand-raised to allow repeat testing over time without chemical restraint. Refraction results were correlated with ultrasound measurements of intraocular dimensions, and with values in adult gazelles. Gazelles are born hyperopic with a mean refractive error of 3.44±0.31 D. By day 50, the animals are virtually emmetropic (0.13±0.21 D) and remain so in adulthood (0.03±0.09 D). The refractive error is highly correlated with the axial length (r²=0.96) and with the vitreous chamber depth (r²=0.83), but not with anterior chamber depth. Significant with-the-rule astigmatism was recorded (P<0.001).