Actin-based vesicular transport in the first 20 min after dusk is crucial for daily rhabdom synthesis in the compound eye of the grapsid crab Hemigrapsus sanguineus

In the crab Hemigrapsus sanguineus, maintained under a 12 h:12 h light:dark cycle, the amount of vesicular smooth endoplasmic reticulum (vesicular sER) in the photoreceptor cell body increases after the light is turned off. This paper demonstrates that actin filaments in the photoreceptor cell body are involved in the transport of vesicular sER towards the rhabdom. To specify the time of actin contribution to rhabdom synthesis, we disrupted the organization of actin filaments in the cell body with cytochalasin D at various time around dusk. We then measured the rhabdom size and also examined the ultrastructure of the photoreceptor cell body 3 h after extinguishing the light. When cytochalasin D was applied from either 1 h before or immediately after extinguishing the light, the rhabdom size did not increase, whereas vesicular sER accumulated in the cell body. In contrast, cytochalasin D applied to the eyes from 20 min after turning the light off did not inhibit rhabdom synthesis. These results indicate that the first 20 min after the light is turned off is particularly important for the transport of vesicular sER towards the rhabdom by the cell body actin filaments

Appearance of Opsin-containing Vesicles as Rhabdomeric Precursors and Their Incorporation into the Rhabdom around Dusk in the Compound Eye of the Crab, Hemigrapsus sanguineus

This paper presents immunocytochemical, freeze-fracture, and fine-structural evidence for the hypothesis that the precursors of the rhabdomeric membranes are vesicles in the photoreceptors of the crab Hemigrapsus sanguineus. The number of vesicles starts to increase in the photoreceptor cell body at midday and peaks at approximately one hour before light-off. The vesicles move toward the rhabdom: they almost disappear from the cell body within the first hour after light-off. As they move, the rhabdom area increases. Electron microscopic immunocytochemistry and freeze-fracture EM revealed that the vesicles contain the visual pigment opsin as an integral membrane protein. Based on detailed observation at the microvillar base by conventional electron microscopy, we present a model of how the vesicles are incorporated into the rhabdom to elongate the rhabdomeric microvilli

Neuronal Sensitivity to Microsecond Time Disparities in the Electrosensory System of Gymnarchus niloticus

To perform the jamming avoidance response (JAR), the weakly electric fish Gymnarchus detects time disparities on the order of microseconds between electrosensory signals received by electroreceptors in different parts of the body surface. This paper describes time-disparity thresholds of output neurons of the electrosensory lateral line lobe (ELL), where the representation of timing information is converted from a time code to a firing-rate code. We recorded extracellular single-unit responses from pyramidal cells in the ELL to sinusoidally modulated time disparity with various depths (0-200 μs). Threshold sensitivity to time disparities measured in 123 units ranged from 0.5 to 100 μs and was ≤5 μs in 60% of the units. The units from pyramidal cells in the inner and outer cell layers of the ELL responded equally well to small time disparities. The neuronal thresholds to time disparities found in the ELL are comparable with those demonstrated in behavioral performance of the JAR. The sensitivity of ELL units to small time disparities was unaffected when the center of the cyclic time-disparity modulation was shifted over a wide range (up to 250 μs), indicating an adaptation mechanism for steady-state time disparities that preserves the sensitivity to small dynamic changes in time disparities. Phase-locked input neurons, which provide time information to the ELL by phase-locked firing of action potentials, did not adapt to steady-state time shifts of sensory signals. This suggests that the adaptation emerges within the ELL

"Double eyes” sign of congenital bilateral dacryocystoceles

Dacryocystocele is caused by nasolacrimal duct obstruction and results in cystic dilatation of the proximal part of the nasolacrimal duct, which is located inferomedial to the orbit, leading to fluid accumulation. It is important to consider that persistent congenital bilateral dacryocystoceles may cause neonatal nasal obstruction resulting in respiratory difficulty, and large dacryocystoceles may require surgical drainage. Ultrasonography demonstrates that congenital bilateral dacryocystoceles and normal eyeballs prenatally resemble two pairs of cystic "lesions” of different sizes. We herein present a case of prenatally diagnosed isolated congenital bilateral dacryocystoceles and propose the new name of "double eyes” sign for this rare condition to create an impact on medical students and resident

Eyes with basic dorsal and specific ventral regions in the glacial Apollo, Parnassius glacialis (Papilionidae)

Recent studies on butterflies have indicated that their colour vision system is almost species specific. To address the question of how this remarkable diversity evolved, we investigated the eyes of the glacial Apollo, Parnassius glacialis, a living fossil species belonging to the family Papilionidae. We identified four opsins in the Parnassius eyes – an ultraviolet- (PgUV), a blue- (PgB), and two long wavelength (PgL2, PgL3)-absorbing types – and localized their mRNAs within the retina. We thus found ommatidial heterogeneity and a clear dorso-ventral regionalization of the eye. The dorsal region consists of three basic types of ommatidia that are similar to those found in other insects, indicating that this dorsal region retains the ancestral state. In the ventral region, we identified two novel phenomena: co-expression of the opsins of the UV- and B-absorbing type in a subset of photoreceptors, and subfunctionalization of long-wavelength receptors in the distal tier as a result of differential expression of the PgL2 and PgL3 mRNAs. Interestingly, butterflies from the closely related genus Papilio (Papilionidae) have at least three long-wavelength opsins, L1–L3. The present study indicates that the duplication of L2 and L3 occurred before the Papilio lineage diverged from the rest, whereas L1 was produced from L3 in the Papilio lineage

Glass scales on the wing of the swordtail butterfly Graphium sarpedon act as thin film polarizing reflectors

The wings of the swordtail butterfly Graphium sarpedon (the Common Bluebottle) have blue/green-colored patches that are covered on the underside by two types of scales: white and glass scales. Transmission and scanning electron microscopy revealed that the white scales are classically structured: the upper lamina, with prominent ridges and large open windows, is well separated by trabeculae from a flat, continuous lower lamina. In the glass scales, the upper lamina, with inconspicuous ridges and windows, is almost flat and closely apposed to the equally flat lower lamina. The glass scales thus approximate ideal thin films, in agreement with the observation that they reflect light directionally and are iridescent. Reflectance and transmittance spectra measured from the glass scales with a microspectrophotometer agree with spectra calculated for an ideal non-absorbing thin film. Imaging scatterometry of single, isolated glass scales demonstrated that the reflected light can be strongly polarized, indicating that they function as polarizing reflectors

Defective phototransductive disk membrane morphogenesis in transgenic mice expressing opsin with a mutated N-terminal domain

Retinitis pigmentosa is a heterogeneous group of inherited retinal disorders in which the photoreceptor cells degenerate. A line of transgenic mice expresses a mutant opsin gene that encodes three missense mutations near the amino terminus, including P23H, which is the basis for a common form of dominant retinitis pigmentosa. By studying the photoreceptor cells of these mice and their normal littermates, we found that: (1) opsin was routed correctly, (2) the concentration of opsin in the disk membranes appeared normal by freeze fracture analysis, (3) the amount of disk membrane shedding was normal, but (4) the basal disks of the outer segments were disorganized, indicating defective disk membrane morphogenesis. Defective disk membrane morphogenesis appears to result in the formation of fewer mature disks, thus accounting for observed gradual shortening of the photoreceptor outer segments with age. We suggest that abnormal disk membrane morphogenesis is the primary cellular defect that leads to blindness, and that it arises from the inability of nascent disk membranes, containing normal and mutant opsin, to interact normally with each other

Serum Vaspin Concentrations Are Closely Related to Insulin Resistance, and rs77060950 at SERPINA12 Genetically Defines Distinct Group with Higher Serum Levels in Japanese Population

Context: Vaspin is an adipokine with insulin-sensitizing effects identified from visceral adipose tissues of genetically obese rats. Objective: We investigated genetic and nongenetic factors that define serum concentrations of vaspin. Design, Setting and Participants: Vaspin levels were measured with RIA in Japanese subjects with normal fasting plasma glucose (NFG; n = 259) and type 2 diabetes patients (T2D; n = 275). Single nucleotide polymorphisms (SNP) at SERPINA12 (vaspin) gene locus were discovered, and five SNP were genotyped in the subjects with varied body mass index (n = 1138). Results: The level of serum vaspin in 93% of the samples was found to vary from 0.2 to nearly 2 ng/ml in NFG subjects (n = 259) and from 0.2 to nearly 3 ng/ml in T2D patients (n = 275) (Vaspin(Low) group), whereas a significant subpopulation (7%) in both groups displayed much higher levels of 10-40 ng/ml (Vaspin(High) group). In the Vaspin(Low) group, serum vaspin levels in T2D were significantly higher than healthy subjects (0.99 +/- 0.04 vs. 0.86 +/- 0.02 ng/ml; P < 0.01). Both in T2D and genotyped Japanese population, serum vaspin levels closely correlated with homeostasis model of assessment for insulin resistance rather than anthropometric parameters. By genotyping, rs77060950 tightly linked to serum vaspin levels, i.e. CC (0.6 +/- 0.4 ng/ml), CA (18.4 +/- 9.6 ng/ml), and AA (30.5 +/- 5.1 ng/ml) (P < 2 x 10(-16)). Putative GATA-2 and GATA-3 binding consensus site was found at rs77060950. Conclusions: Serum vaspin levels were related to insulin resistance, and higher levels of serum vaspin in 7% of the Japanese population are closely linked to minor allele sequence (A) of rs77060950. (J Clin Endocrinol Metab 97: E1202-E1207, 2012