scholarly journals Regionalization in the compound eye of Talitrus saltator (Crustacea, Amphipoda)

2019 ◽  
Author(s):  
Alice Ciofini ◽  
Luca Mercatelli ◽  
Yumi Yamahama ◽  
Takahiko Hariyama ◽  
Alberto Ugolini
Keyword(s):  
Compound Eye ◽  
Wavelength Region ◽  
Ventral Part ◽  
Dorsal Part ◽  
Blue Filter ◽  
Talitrus Saltator ◽  
Summary Statement ◽  
Celestial Compass ◽  
Behavioural Experiments ◽  
Retinular Cells

AbstractThe crustacean Talitrus saltator is known to use many celestial cues during its orientation along the sea-land axis of sandy shores. In this paper, we investigated the existence of the eye regionalization by morphological, electrophysiological and behavioural experiments. Each ommatidium possesses five radially arranged retinular cells producing a square fused rhabdom by R1-R4 cells; the smaller R5 exist between R1 and R4. The size of R5 rhabdomere is largest in dorsal part and becomes gradually smaller in median and ventral part of the eye. Spectral-sensitivity measurements were recorded from either dorsal or ventral parts of the compound eye to clarify the chromatic difference. Results show that the dorsal part is green and UV-blue dichromatic, whereas the ventral part is UV (390 nm) with a substantial population of 450 nm receptors with the responses in the longer wavelength region. To evaluate the orienting behaviour of individuals, their eyes were black painted either in the dorsal or ventral part, under natural sky or a blue filter with or without the vision of the sun. Results show that animals painted on the dorsal part of their eyes tested under the screened sun were more dispersed and in certain cases their directions deflected than other groups of individuals. Furthermore, sandhoppers subjected to the obscuring of this area met in any case high difficulties in their directional choices. Therefore, our present work indicates the existence of a regionalization of the compound eye of T. saltator.Summary statementThis work provides evidences of the morphological and electrophysiological regionalization of the compound eye and the visual capabilities for behaviour involved in the recognition of the celestial compass orienting factors in crustaceans.

Fine structure of the compound eye of the black fly Simulium vittatum (Diptera: Simuliidae)

1987 ◽  
Vol 65 (6) ◽  
pp. 1454-1469 ◽  
Author(s):  
Gail E. O'Grady ◽  
Susan B. McIver
Keyword(s):  
Fine Structure ◽  
Compound Eye ◽  
Sensory Receptor ◽  
Dorsal Region ◽  
Male And Female ◽  
Simulium Vittatum ◽  
Transmission Electron ◽  
Accessory Pigment ◽  
Open Rhabdom ◽  
Retinular Cells

The fine structure of the ommatidia in light- and dark-adapted eyes of male and female Simulium vittatum Zetterstedt was investigated using scanning and transmission electron microscopy. The male eye is divided into distinct dorsal and ventral regions. The facets in the dorsal region are approximately two times larger than those in the ventral one, which are similar in size to the ones in the female eye. All ommatidia of S. vittatum examined consist of two general regions: a distal dioptric apparatus with bordering primary and accessory pigment and Semper cells, and a sensory receptor layer. Each ommatidium in the female eye and ventral eye of the male has eight retinular cells (R cells): six peripheral (R1–6) and two central (R7, R8). R7 occurs distally and R8 basally. Strikingly, the ommatidia in the dorsal eye of the male lack the R7 cell. In all ommatidia, rhabdomeres on the inner surface of the peripheral R cells are separate throughout their length, creating an open rhabdom. A greater diameter of corneal facets, elongated peripheral R cells, and perhaps the lack of the R7 cell are specializations of the dorsal region of the eye that help the male to detect small, rapidly moving females against the skylight as they fly above the swarm of males. Differences observed between light- and dark-adapted eyes of male and female S. vittatum were the same and were associated with the internal components of the peripheral R cells.

Morphological and ontogenetic studies in Plams. IV. Ontogeny of the vasuclar pattern in four Genera

1966 ◽  
Vol 14 (3) ◽  
pp. 277 ◽  
Author(s):  
K Periasamy
Keyword(s):  
Temporal Sequence ◽  
Mature Leaf ◽  
Ventral Part ◽  
Dorsal Part ◽  
Basic Pattern ◽  
Line Parallel ◽  
Basal Half ◽  
Two Sides ◽  
Different Parts

The median dorsal strand is the first to differentiate in Cocos, Phoenix, and Caryota. It traverses the terminal abaxial ridge of the plications, to end at the apex of the non-plicate margin of the lamina wing. The series of strands that afterwards differentiate tangentially on either side of it form the first vasculature of the adaxial ridges of the plications, and are termed "primary strands". In Borassus, the median dorsal strand differentiates only after 5-10 pairs of primary strands are differentiated. In Cocos and Borassus, each primary strand traverses one adaxial ridge; hence the primary strands are more or less equal in number to the pinnae in Cocos and the segments in Borassus. In Phoenix, each primary strand executes an almost right-angled, adaxial curve at its tip and branches dichotomously into two to four branches, each traversing a line parallel to an adaxial ridge, in the "haut" formed by the fusion of the adaxial ridges with each other. Therefore the primary strands are characteristically fewer than the pinnae. In addition to the branches that vascularize the haut, the primary strands make connections later with some of the strands of the pinnae that differentiate in the lamina. When the haut is shed, those parts of the branches of the primary strands situated in the haut are lost, leaving the primary strands connected to the laminar strands alone. In Borassus, during dissection of the palmate lamina, those parts of the primary strands situated in the apical halves of the adaxial ridges are constricted, along with the surrounding ridge, and shed. In the basal half of the adaxial ridge, the primary strand makes connections with other neighbouring strands of the lamina. In Caryota, the primary strands are comparatively few, since the primary plications are few. The strands formed adaxial and abaxial to the tangential row of primary strands are irregularly disposed, and are termed the adaxiai and abaxial complexes respectively. These strands vascularize the rest of the lamina, and also the adaxial ridges. The strands of the adaxial complex of Cocos are inversely oriented. The primary strands extend to the thin ventral part of the sheathing base in Cocos, Borassus, and Caryota, but are confined to the thick dorsal part in Phoenix. The oblique courses of the strands on the two sides of the median ventral line of the sheath as mirror images of one another, and their spatial and temporal sequence of differentiation along two different transverse depths, account for their remarkable interlocking as "warps and wefts" along the median ventral line. The primary strands differentiate acropetally. The adaxial and the abaxial strands show acropetal, basipetal, or discontinuous differentiation in different parts of the leaf. Although the basic pattern of vasculature seen in the younger stages does not change, the vasculature of the mature leaf becomes very complex by the formation of numerous additional bundles and branches, and their anastomoses, especially in the sheath and rachis.

scholarly journals Ultrastructure within the Lateral Plexus of the Limulus Eye

1972 ◽  
Vol 59 (3) ◽  
pp. 285-304 ◽  
Author(s):  
Moshe Gur ◽  
Richard L. Purple ◽  
Russell Whitehead
Keyword(s):  
Lateral Inhibition ◽  
Serial Section ◽  
Compound Eye ◽  
Branching Pattern ◽  
Synaptic Contacts ◽  
Ribbon Synapses ◽  
Section Technique ◽  
Transmitter Substance ◽  
Horizontal Spread ◽  
Retinular Cells

The ultrastructure of the lateral plexus in the compound eye of Limulus is investigated by serial section technique. "Cores" of tissue containing the axons, lateral plexus, and neuropile associated with one sensory ommatidium show the following features: (a) collateral branches from retinular cells do not contribute to the lateral plexus proper, but do form retinular neuropile by contacting collaterals of a self-contained cluster of retinular axons; (b) collateral branches from eccentric cell axons always branch repeatedly upon leaving the parent axon, and compose the bulk of the lateral plexus; (c) the most distal collateral branches from an eccentric cell axon appear to form neuropile and synaptic contacts with each other, whereas more proximal branches form synaptic contacts with collaterals from eccentric cell axons of neighboring ommatidia. We conclude that the ribbon synapses and associated transmitter substance in eccentric cell collaterals must be inhibitory, and that two pathways for self-inhibition may exist. We suggest, as a working hypothesis for the structure of the lateral plexus, a branching pattern with depth that mirrors the horizontal spread of lateral inhibition measured physiologically.

scholarly journals A lateralised design for the interaction of visual memories and heading representations in navigating ants

2020 ◽  
Author(s):  
Antoine Wystrach ◽  
Florent Le Moël ◽  
Leo Clement ◽  
Sebastian Schwarz
Keyword(s):  
Brain Area ◽  
Computational Modelling ◽  
Motor Command ◽  
Central Complex ◽  
Stage Process ◽  
Celestial Compass ◽  
Left And Right ◽  
Behavioural Experiments ◽  
New Perspective

AbstractThe navigational skills of ants, bees and wasps represent one of the most baffling examples of the powers of minuscule brains. Insects store long-term memories of the visual scenes they experience 1, and they use compass cues to build a robust representation of directions 2,3. We know reasonably well how long-term memories are formed, in a brain area called the Mushroom Bodies (MB) 4–8, as well as how heading representations are formed in another brain area called the Central Complex (CX) 9–12. However, how such memories and heading representations interact to produce powerful navigational behaviours remains unclear 7,13,14. Here we combine behavioural experiments with computational modelling that is strictly based on connectomic data to provide a new perspective on how navigation might be orchestrated in these insects. Our results reveal a lateralised design, where signals about whether to turn left or right are segregated in the left and right hemispheres, respectively. Furthermore, we show that guidance is a two-stage process: the recognition of visual memories – presumably in the MBs – does not directly drive the motor command, but instead updates a “desired heading” – presumably in the CX – which in turn is used to control guidance using celestial compass information. Overall, this circuit enables ants to recognise views independently of their body orientation, and combines terrestrial and celestial cues in a way that produces exceptionally robust navigation.

The Dorsal Compound Eye of Simuliid Flies:

1976 ◽  
Vol 31 (11-12) ◽  
pp. 764-765 ◽  
Author(s):  
K. Kirschfeld ◽  
P. Wenk
Keyword(s):  
Compound Eye ◽  
Quantum Noise ◽  
Quantum Fluctuations ◽  
Limiting Factor ◽  
Light Quantum ◽  
Small Animals ◽  
Physical Limit ◽  
Behavioural Experiments

Abstract Compound Eye, Light-Quantum Noise The highly specialized dorsal compound eye of male Simuliids is especially adapted to detect during flight the females which are very small animals (1×3 mm). At dawn, the eye functions close to the physical limit imposed by the quantum fluctuations of light. In bright illuminations, light-qauntum noise is not a limiting factor as can be shown by behavioural experiments.

Two opsins from the compound eye of the crab Hemigrapsus sanguineus

1996 ◽  
Vol 199 (2) ◽  
pp. 441-450 ◽  
Author(s):  
K Sakamoto ◽  
O Hisatomi ◽  
F Tokunaga ◽  
E Eguchi
Keyword(s):  
Photoreceptor Cell ◽  
Compound Eye ◽  
Visual Pigments ◽  
Amino Acid Residues ◽  
Hemigrapsus Sanguineus ◽  
Brachyuran Crab ◽  
Maximal Absorption ◽  
Retinular Cells ◽  
Cdna Nucleotide

The primary structures of two opsins from the brachyuran crab Hemigrapsus sanguineus were deduced from the cDNA nucleotide sequences. Both deduced proteins were composed of 377 amino acid residues and included residues highly conserved in visual pigments of other species, and the proteins were 75 % identical to each other. The distribution of opsin transcripts in the compound eye, determined by in situ hybridization, suggested that the mRNAs of the two opsins were expressed simultaneously in all of the seven retinular cells (R1-R7) forming the main rhabdom in each ommatidium. Two different visual pigments may be present in one photoreceptor cell in this brachyuran crab. The spectral sensitivity of the compound eye was also determined by recording the electroretinogram. The compound eye was maximally sensitive at about 480 nm. These and previous findings suggest that both opsins of this brachyuran crab produce visual pigments with maximal absorption in the blue-green region of the spectrum. Evidence is presented that crustaceans possess multiple pigment systems for vision.

Packaging of rhodopsin and porphyropsin in the compound eye of the crayfish

1993 ◽  
Vol 10 (2) ◽  
pp. 193-202 ◽  
Author(s):  
Joel Zeiger ◽  
Timothy H. Goldsmith
Keyword(s):  
Visual Pigment ◽  
Regional Variation ◽  
Compound Eye ◽  
Procambarus Clarkii ◽  
Difference Spectra ◽  
Retinular Cells ◽  
Different Levels

AbstractThe distribution of 3-dehydroretinal (Ral2) in dorsal, middle, and ventral slices of eyes of the crayfish Procambarus clarkii was examined by HPLC. No pronounced differences were found. Similar results were obtained when the eyes were cut into anterior, intermediate, and posterior portions.Dichroic difference spectra were measured in single halves of microvillar layers of isolated rhabdoms and the proportions of rhodopsin (P1) and porphyropsin (P2) estimated by comparison with computer-generated mixtures of these pigments, whose spectra are known from previous work. The fraction of visual pigment that is porphyropsin appears to be uniform throughout individual retinular cells and among the retinular cells of individual rhabdoms, but various substantially among different rhabdoms from the same eye.The interommatidial variation in the amount of P2 greatly exceeds the gross regional variation in Ral2. This means there is an intermingling of ommatidia with different levels of P2. The variability in P2 among ommatidia is not likely to have important implications for the vision of the crayfish but suggests that in the metabolism of retinoids, individual ommatidia are quasi-independent metabolic units. The results are compatible with a single opsin for both crayfish rhodopsin and porphyropsin.

scholarly journals Some aspects of vision in the lobster, Homarus vulgaris, in relation to the structure of its eye

1963 ◽  
Vol 43 (3) ◽  
pp. 683-699 ◽  
Author(s):  
Elizabeth M. Kampa ◽  
Bernard C. Abbott ◽  
Brian P. Boden
Keyword(s):  
Compound Eye ◽  
Crystalline Cone ◽  
Cone Cells ◽  
Retinular Cells

The compound eye of the lobster H. vulgaris has a single lobe; its ommatidia are uniform except in length. Each ommatidium consists of a corneal facet, two corneagenous cells, four cone cells, a four-part crystalline cone, an elongate cone stalk, seven retinular cells and a four-part rhabdom. Growth between the zoaeal and adult stages is primarily a lengthening of the cone stalk.

‘Nemacheilus’ argyrogaster, a new species of loach from southern Laos (Teleostei: Nemacheilidae)

Zootaxa ◽  
2021 ◽  
Vol 4933 (2) ◽  
pp. 277-288
Author(s):  
MAURICE KOTTELAT
Keyword(s):  
New Species ◽  
Southeast Asia ◽  
The Body ◽  
Colour Pattern ◽  
Flowing Water ◽  
Ventral Part ◽  
Dorsal Part ◽  
Posterior Edge ◽  
Lower Lip ◽  
A New Species

‘Nemacheilus’ argyrogaster, new species, is described from the Xe Kong, Mekong drainage, in Attapeu and Xe Kong provinces, southern Laos. It is distinguished from all other Nemacheilidae in Southeast Asia by its unique colour pattern made of a bold black midlateral stripe separating the yellowish brown dorsal part of the body from the silvery whitish ventral part and a middorsal row of 14–19 thin saddles. Besides, the male has a globulous suborbital flap with tubercles along its free, posterior edge, and the pectoral fin with thickened anterior ray and branched rays 1–4 and unculiferous pads behind them covered by small tubercles; lips thin, lower lip continuous with a narrow median notch. It was found in moderate to fast flowing water, over pebble to stone bottom. ‘Nemacheilus’ argyrogaster, was earlier misidentified as N. longistriatus; it is provisionally placed in the genus Nemacheilus. 

scholarly journals Feather loss in laying hens

2006 ◽  
Vol 60 (1-2) ◽  
pp. 107-114
Author(s):  
Slavca Hristov ◽  
Sreten Mitrovic ◽  
Mirjana Todorovic ◽  
Vladan Djermanovic ◽  
Ivica Cvetkovic
Keyword(s):  
Sequence Analysis ◽  
Laying Hens ◽  
The Other ◽  
Ventral Part ◽  
Dorsal Part ◽  
Detailed Consideration ◽  
Video Recordings ◽  
One Year ◽  
The One ◽  
Comparison Of The Results

The paper examined the incidence of different forms of feather loss and cannibalism in laying hens aged 74 weeks following moulting and in laying hens following exploitation for a period of one year. The forms of feather loss were considered in detail through a repeated examination of video recordings and they were sorted according to localization - to feather loss on the ventral part of the neck, on the dorsal part of the neck, and on the back between the wings. Feather loss on the ventral part of the neck was established in 47.9% hens, and in the dorsal part in 16.77% hens of the 167 laying hens aged 74 weeks following moulting. The group of 129 laying hens that were observed following one-year exploitation exhibited considerably more frequent feather loss, in 96.90% hens it was localized on the ventral part of the neck, in 60.47% hens on the dorsal part of the neck, and in 20.16% hens it was localized on the back between the wings. A comparison of the results of the incidence of co localized forms of feather loss in the one and the other group of laying hens using the t-test showed statistically very significant differences. A detailed consideration of the video recordings using the method of sequence analysis did not reveal any cannibalism in either group of laying hens.

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