Search Results - (Author, Cooperation:D. O'Carroll)

2011-10-25

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Alleles ; Animals ; Argonaute Proteins/genetics/*metabolism ; DNA Transposable Elements/genetics ; *Gene Silencing ; Long Interspersed Nucleotide Elements/*genetics ; Male ; Mice ; RNA, Small Interfering/*biosynthesis/*genetics/metabolism ; RNA-Binding Proteins/genetics/metabolism ; Spermatogenesis/genetics

2013-12-07

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; Corpus Striatum/cytology ; Dendrites/physiology ; Epilepsy/metabolism ; Hyperkinesis/metabolism ; MAP Kinase Signaling System ; Mice ; MicroRNAs/genetics/*metabolism ; Mitogen-Activated Protein Kinase 1/antagonists & inhibitors/metabolism ; Mitogen-Activated Protein Kinase 3/antagonists & inhibitors/metabolism ; *Motor Activity ; Neurons/*physiology ; Parkinsonian Disorders/metabolism/physiopathology ; Prosencephalon/cytology/*physiology ; RNA, Messenger/genetics/metabolism ; RNA-Induced Silencing Complex/metabolism ; Up-Regulation

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] In the blowfly Calliphora, wide-field, direction-selective neurons of the third optic ganglion are a major component of the optomotor pathway for flight stabilization14. We used drifting, sinusoidal gratings to determine the temporal and spatial frequency tuning of similar neurons in ten insect ...

Electronic Resource

1432-1351

Insect vision ; Amacrine cell ; Visual processing ; Neural circuitry ; Neurobiotin ; Synaptology

Springer Online Journal Archives 1860-2000

Biology

Medicine

Summary 1. The proximal part of the medulla of the locust (Locusta migratoria) optic lobe contains a small number of tangential amacrine cells. Using the recently developed intracellular label, Neurobiotin, we have combined physiological characterisations with structural descriptions of the cells at light and at electron microscopic levels. 2. Each of these tangential medulla amacrine (TMA) cells arborises over a large portion of the visual field (Fig. 1), with strongly beaded dendrites restricted to the layer of the medulla immediately proximal to the large serpentine layer that divides the ganglion. There is a second, more sparse and finer arborisation in the most proximal layer of the medulla. 3. Using our own modification of Neurobiotin histochemistry for transmission electron microscopy, we investigated the synaptology of the TMA cells. In the principal layer of dendrites, TMA cells make both input and output synapses with the same cells. Thus the TMA cells might act to connect one (or more) classes of columnar cells, providing a substrate for lateral interactions between retinotopic afferent pathways. The “beads” seen at the LM level are due to aggregations of mitochondria and not to synaptic terminals. 4. Physiologically these TMA cells are transient (on/ off) units. Whilst their arborisation is extensive, the “receptive field” measured in a single recording is only about 20° across. 5. These TMA cells appear suited to mediating the inhibitory interaction between the columnar inputs to the lobula giant movement detector (LGMD) that accounts for the preference of the latter cell for small targets.

Electronic Resource

1432-1351

Key words Vision ; Photoreceptor ; Insect ; Thermoregulation ; Temporal acuity

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract A hot head gives an insect a clearer view of a moving world because warming reduces motion blur by accelerating photoreceptor responses. Over a natural temperature range, 19–34 °C, the speed of response of blowfly (Calliphora vicina) photoreceptors more than doubles, to produce the fastest functional responses recorded from an ocular photoreceptor. This acceleration increases temporal resolving power, as indicated by the corner frequency of the response power spectrum. When light adapted, the corner frequency increases from 53 Hz to 119 Hz with a Q 10 of 1.9, and when dark adapted from 8 Hz to 32 Hz with a Q 10 of 3.0. Temperature sensitivity originates in the phototransduction cascade, and is associated with signal amplification. The temperature sensitivity of photoreceptors must be taken into account when studying the mechanisms, function and ecology of vision, and gives a distinct advantage to insects that thermoregulate.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] Some insects and vertebrates use the pattern of polarized light in the sky as an optical compass. Only a small section of clear sky needs to be visible for bees and ants to obtain a compass bearing for accurate navigation. The receptors involved in the polarization compass are confined to a ...

Electronic Resource

1432-0878

Principal eye ; Layer I receptors ; Mosaic organisation ; Light guides ; Retinal morphogenesis ; Retinal evolution ; Jumping spiders (Salticidae)

Springer Online Journal Archives 1860-2000

Biology

Medicine

Summary Previous work has shown that the mosaics of Layer I receptive segments in the tiered principal (AM) retinae of most jumping spiders (Salticidae) are organised as regular arrays of light guides which are competent to sustain fine visual discriminations. The retinae are narrow strips which arise in development by lateral compression of a primordial hemispherical monolayer of nascent receptive segments. Foveal Layer I receptive segments each contain a single rhabdomere in most species, but simple geometry suggests that the developmental route will generate a vertical ‘suture line’ of sampling ambiguity in which contiguous rhabdomeres of adjacent segments act as single light guides. In members of two primitive subfamilies, the Lyssomaninae and Spartaeinae, such suture lines are indeed present; their optical consequences are discussed in the context of the evolution of foveal rhabdomeres that are long light guides. In several notionally advanced subfamilies collectively termed the Salticinae here for convenience, suture lines have been eliminated by rotations of the positions of single rhabdomeres with respect to the longitudinal axes of their receptive segments. The resulting mosaic patterns of rhabdomere distribution are similar in genera distantly related within the Salticinae, and are not bilaterally symmetrical with respect to horizontal axes bisecting the boomerang-shaped receptor fields. The basic pattern is not disturbed in genera in which Layer I receptive segments are separated from neighbours by a structureless extracellular matrix. This separation of segments conserves the organisation found in juvenile jumping spiders designated as 2nd instar by Blest (1988). The present material confirms that the evolution of retinal tiering preceded that of a foveal Layer I mosaic of high acuity in the Lyssomaninae as well as Spartaeinae (Blest and Carter 1987). The evolutionary history of Layer I in the Salticinae remains obscure.

Electronic Resource