Characteristics of corneal lens chitin in dragonfly compound eyes

1978 ◽

Vol 36 (2) ◽

pp. 604-605

Author(s):

Janice E. Kuster

Keyword(s):

Endoplasmic Reticulum ◽

Fine Structure ◽

Rough Endoplasmic Reticulum ◽

Cell Nucleus ◽

The Other ◽

Pigment Cells ◽

Compound Eyes ◽

Basal Bodies ◽

Protein Deposits ◽

Corneal Lens

The fine structure of photopic eucone eyes of Cicindela tranquebarica adults was examined using cryofracture SEM, TEM, and freeze-etch techniques. A “subcorneal layer” can be distinguished between the corneal lens and crystalline cone. In surface view (Fig. 1) this layer consists of concave polygons (po). It has parabolic lamellae (lm) of endocuticle consisting of microfibrils (mf) having a chitin core with protein deposits along their lengths (Fig. 2). Two primary pigment cells (lp) are devoid of pigment granules, but are rich in rough endoplasmic reticulum (rer) and surround a crystalline thread (ct) (Fig. 3). Extensions of the crystalline thread form inter-retinular fibers (f) containing microtubules between retinula cells 1/2, 3/4, 5/6, and 7/1 (Figs. 4, 5).Distal to each retinula cell nucleus are two basal bodies (bb), one perpendicular to the other (Fig. 4). The proximal body extends two fibrillar feet which fuse to form a horizontally banded ciliary rootlet which extends the retinula length peripheral to the rhabdom.

Download Full-text

Trilobite vision: a comparison of schizochroal and holochroal eyes with the compound eyes of modern arthropods

The Paleontological Society Special Publications ◽

10.1017/s2475262200006638 ◽

1992 ◽

Vol 6 ◽

pp. 103-103

Author(s):

David. Fordyce ◽

Thomas W. Cronin

Keyword(s):

Visual Field ◽

National Science Foundation ◽

Compound Eye ◽

Visual Fields ◽

Visual Space ◽

Compound Eyes ◽

Central Processing ◽

Corneal Lens ◽

Bright Sunlight ◽

Parameter Values

The compound eyes of trilobites provide the best examples of fossilized sensory organs for which the function in life can be worked out today, because the optical array of their corneal lenses preserves the geometry with which the eye originally sampled the visual world. An analysis of trilobite vision is strengthened by the use of new mathematical approaches to compound eye design. In particular, the product of the facet diameter (D) and the interommatidial angle (Δϕ) gives the value of the eye parameter, DΔϕ, which is a reliable indicator of the photic conditions in which the eye was used. In modern arthropods, DΔϕ values range from 0.3 for animals active in bright sunlight to 20 or more for nocturnal or deep-sea animals.Three types of compound eyes existed in trilobites: schizochroal, holochroal, and abathochroal. We examined the schizochroal and holochroal types. Schizochroal eyes were studied in the phacopid species Phacops rana crassituberculata and Phacops rana milleri. We measured the diameter of every corneal lens, and estimated its optical axis by taking the normal to the plane of the lens's diameter. In both species, each eye covered almost exactly 180° of visual space in azimuth with no binocular overlap, from directly anterior to directly posterior. Vertically, the visual field extended from the horizon to about 40° in elevation. Facet diameters and interommatidial angles were large, giving eye parameter values ranging from 10 to > 150. These are much greater than in any living arthropod, implying that modern compound eye theory does not apply to schizochroal eyes. We believe that each ommatidium of the schizochroal eye served as a miniature lens eye. If so, phacopid vision must have been unique, with multiply overlapping visual fields. Such a design would have required considerable central processing, but could have provided exceptional opportunities for spatial, spectral, and polarizational analysis.We examined holochroal compound eyes in Asaphus cornutus and Isotelus “gigas”. Here, visual field coverage was greater than in the schizochroal eye type, with a small amount of frontal binocular overlap. Holochroal eyes contain far more ommatidia than do schizochroal types, reducing both facet diameter (D) and interommatidial angle (Δϕ). Thus, DΔϕ values in these species fall into the same range as in modern compound eyes. This implies that function of the holochroal eye was similar to that of modern crustaceans and insects.This material is based on research supported by the National Science Foundation under Grants No. BNS-8518769 and BNS-8917183.

Download Full-text

Differentiation Processes of the Ocellar Retina of the Honeybee (Apis Mellifera L.)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100159692 ◽

1990 ◽

Vol 48 (3) ◽

pp. 430-431

Author(s):

Maria Anna Pabst

Keyword(s):

Apis Mellifera ◽

Distal Part ◽

Cell Layer ◽

Single Layer ◽

Photoreceptor Cells ◽

Distal Segment ◽

Compound Eyes ◽

Thin Sections ◽

Ultrastructural Studies ◽

Adult Worker

In addition to the compound eyes, honeybees have three dorsal ocelli on the vertex of the head. Each ocellus has about 800 elongated photoreceptor cells. They are paired and the distal segment of each pair bears densely packed microvilli forming together a platelike fused rhabdom. Beneath a common cuticular lens a single layer of corneagenous cells is present.Ultrastructural studies were made of the retina of praepupae, different pupal stages and adult worker bees by thin sections and freeze-etch preparations. In praepupae the ocellar anlage consists of a conical group of epidermal cells that differentiate to photoreceptor cells, glial cells and corneagenous cells. Some photoreceptor cells are already paired and show disarrayed microvilli with circularly ordered filaments inside. In ocelli of 2-day-old pupae, when a retinogenous and a lentinogenous cell layer can be clearly distinguished, cell membranes of the distal part of two photoreceptor cells begin to interdigitate with each other and so start to form the definitive microvilli. At the beginning the microvilli often occupy the whole width of the developing rhabdom (Fig. 1).

Download Full-text

New species of bristletails of the genus Lepismachilis (Archaeognatha: Machilidae) from Serbia and Montenegro

Acta Entomologica Musei Nationalis Pragae ◽

10.2478/aemnp-2018-0049 ◽

2018 ◽

Vol 58 (2) ◽

pp. 577-587

Author(s):

Vladimir Kaplin

Keyword(s):

New Species ◽

Balkan Peninsula ◽

Species Group ◽

Compound Eyes ◽

Serbia And Montenegro ◽

Sensory Field ◽

Fore Femur ◽

Three New Species

Abstract The fauna of bristletails of the genus Lepismachilis Verhoeff, 1910 in Montenegro and Serbia includes only one species L. (Berlesilis) targionii (Grassi, 1887) with 2 + 2 eversible vesicles on abdominal urocoxites II–VI. Three new species of this genus are described: L. (Lepismachilis) prijepolja sp. nov., L. (Lepismachilis) limensa sp. nov. from Serbia, and L. (Lepismachilis) alexandrae sp. nov. from Montenegro. All described new species belong to the species group of the subgenus Lepismachilis s. str. with 2 + 2 eversible vesicles on abdominal urocoxites II–V. Lepismachilis prijepolja sp. nov. differs from L. y-signata Kratochvíl, 1945 and L. notata Stach, 1919 by the color, drawings and ratios of the compound eyes; ratios of sensory field on fore femur of male, number of divisions of ovipositor. Lepismachilis limensa sp. nov. differs from L. hauseri Bitsch, 1974 and L. abchasica Kaplin, 2017 by ratios of paired ocelli, sensory field on fore femur of male; ratios and chaetotaxy of maxillary and labial palps. Lepismachilis alexandrae sp. nov. differs from L. abchasica by the drawings of the compound eyes; ratios of paired ocelli, sensory field on fore femur of male; number of divisions of the parameres and gonapophyses. A list of the Machilidae occurring in Balkan Peninsula is also provided.

Download Full-text

In search of the spectral composition of an effective light trap for the mushroom pest Lycoriella ingenua (Diptera: Sciaridae)

Scientific Reports ◽

10.1038/s41598-021-92230-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sándor Kecskeméti ◽

András Geösel ◽

József Fail ◽

Ádám Egri

Keyword(s):

Light Intensity ◽

Spectral Sensitivity ◽

Fungal Pathogens ◽

Light Trap ◽

Spectral Composition ◽

Wavelength Dependence ◽

Crop Damage ◽

Photon Flux ◽

Compound Eyes ◽

Behavioural Experiments

AbstractCertain fungus gnats, like Lycoriella ingenua are notorious pests in agriculture, especially in mushroom production. While larvae cause mainly direct crop damage, adults are vectors of several dangerous fungal pathogens. To promote the development of pesticide-free management methods, such as light trapping, we measured the spectral sensitivity of L. ingenua compound eyes with electroretinography and performed two different behavioural experiments to reveal the wavelength dependence of phototaxis in this species. The spectral sensitivity of the compound eyes is bimodal with peaks at 370 nm (UV) and 526 nm (green). Behavioural experiments showed that attraction to light as a function of wavelength depends on light intensity. In our first experiment, where the minimal photon flux (105–109 photons/cm2/s) needed for eliciting a phototactic response was determined wavelength by wavelength, phototaxis was strongest in the green spectral range (~526 nm). In the other behavioural experiment, where wavelength preference was tested under a higher but constant light intensity (~1013 photons/cm2/s), the highest attraction was elicited by UV wavelengths (398 nm). Our results suggest that both UV and green are important spectral regions for L. ingenua thus we recommend to use both UV (~370-398 nm) and green (~526 nm) for trapping these insects.

Download Full-text

Dominant Enhancers of Egfr in Drosophila melanogaster: Genetic Links Between the Notch and Egfr Signaling Pathways

Genetics ◽

10.1093/genetics/147.3.1139 ◽

1997 ◽

Vol 147 (3) ◽

pp. 1139-1153 ◽

Cited By ~ 3

Author(s):

James V Price ◽

Edward D Savenye ◽

David Lum ◽

Ashton Breitkreutz

Keyword(s):

Notch Signaling ◽

Signaling Pathways ◽

Growth Factor Receptor ◽

Compound Eyes ◽

Egfr Signaling ◽

Wing Vein ◽

Developmental Context ◽

Epidermal Growth ◽

Hypomorphic Alleles ◽

Complex Signaling

The Drosophila epidermal growth factor receptor (EGFR) is a key component of a complex signaling pathway that participates in multiple developmental processes. We have performed and F1 screen for mutations that cause dominant enhancement of wing vein phenotypes associated with mutations in Egfr. With this screen, we have recovered mutations in Hairless (H), vein, groucho (gro), and three apparently novel loci. All of the E(Egfr)s we have identified show dominant interactions in transheterozygous combinations with each other and with alleles of N or Su(H), suggesting that they are involved in cross-talk between the N and EGFR signaling pathways. Further examination of the phenotypic interactions between Egfr, H, and gro revealed that reductions in Egfr activity enhanced both the bristle loss associated with H mutations, and the bristle hyperplasia and ocellar hypertrophy associated with gro mutations. Double mutant combinations of Egfr and gro hypomorphic alleles led to the formation of ectopic compound eyes in a dosage sensitive manner. Our findings suggest that these E(Egfr)s represent links between the Egfr and Notch signaling pathways, and that Egfr activity can either promote or suppress Notch signaling, depending on its developmental context.

Download Full-text