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Biomedical subjects

E Rosenzweig

Publications and source records attributed to E Rosenzweig.

At least 19 recordsLinked to original sources
PubMed2001

Thermal properties of hornet colonies: thermography of individual hornets and their nests and the role of the pupal silk in thermoregulation.

The present study focused on temperature assessments within a hornet nest. The measurements encompassed adult hornets, brood combs and the various stages of brood, and involved a thermographic method. Body parts of adult hornets were found to vary in their temperature, with the thorax eliciting the highest temperature and the abdomen the lowest. Similarly, there were thermal variances between larvae at instars 4-5, light-colored pupae and dark pupae. The measurements were made at day and night (when the entire population was present in the nest) on nests containing thousands of individuals at various ages. Most of the pupae measured during October were hornet drones. The usual air temperature between the (subterranean) combs was 28.7 degrees C, while the outside (ground level) temperature was 23.5 degrees C. The paper discusses the creation of heat by hornets, the thermoregulation throughout night and day, both by the hornets proper as well as by their products (comb and silk). Also discussed is the intra-nest conversion of one form of energy to another, as heat to electric current or vice versa.

Animals↗
PubMed2001

Navigation and thermophotovoltaic activity by hornets at different light conditions: the influence of UVB blockers.

The aim of the present investigation was two-fold: a) to observe the homing of the Oriental hornet, Vespa orientalis (Hymenoptera, Vespinae) from different distances; and b) to study the photothermoelectric activity of hornet cuticle obtained from the subjects of goal (a) and kept frozen for a number of days prior to its testing. In both the above mentioned phases of the investigation, an attempt was made to assess how the covering of the hornets' cuticle with Ultra Violet B (UVB) blockers affects their activity as compared to the control. Flying hornets were observed to return to the nest from distances of up to 7 km, once they had learned the way back. However, covering of the cuticle with UVB blockers increases the percentage of 'non-returners' to nearly 100%. Covering the cuticle completely or partly with a number of UVB blockers (except for Sisley) proves lethal for the hornets within 24 hours. A statistical model on homing is proposed of the effect of range, of covering with UVB blockers and covering ocelli with Tippex. In the wing of the hornet there is increase in the electric current with rise in the temperature and decrease in the current upon drop of the temperature, but light has no effect on this alar (wing) current. Contrariwise, the body cuticle of the hornet responds to both temperature and illumination in terms of its electric current. Coating of the cuticle with UVB blockers causes in the wing (under all conditions of illumination) and in the cuticle (only in the dark) a moderation in the amplitude of the photothermoelectric current.

Animals↗
PubMed2000

The solar cell in hornet cuticle: nanometer to micrometer scale.

This paper focuses on structures observed by scanning and transmission electron microscopy and atomic force microscopy upon and within the abdominal cuticle of the Oriental hornet, Vespa orientalis. Taken together, these structures form an 'organ' whose function is the absorption ef sunlight and storage of the resultant electrical energy. In principle, this organ resembles a solar cell. The gaster of the hornet is cone-shaped and comprised of the following components: (i) structures protruding from the epicuticular surface, which are arranged lengthwise and generally parallel to one another like furrows; (ii) these furrows overlie straight, terrace-like flat surfaces, which are shaped like imperfect polygons, each about 100 microm2 in area; (iii) each terrace abuts an area that is positioned lower than it, the juncture between the two is comprised of a stripe, which is vertical to the topmost polygonal flat and perpendicular to the furrows; (iv) between the juncture stripes, at distances of 10-100 microm apart, there are smooth flat surfaces reminiscent of a parabolic mirror of about 20 microm2, each possessing a rounded, eccentric area recessed to a depth of about 7.5 microm (i.e. a heat sinking housing), underneath which can be seen the upper part of the peripheral photoreceptor (PP); (v) cuticular lamellae, about 30 in number, create a pore between them in the PP region, fold in vertical fashion and enwrap the entire PP down to its broad base which is immersed in a yellow bacterial layer and where the cuticular layers are very thin. Presumably the light energy impinges vertically upon the individual terraced flat surfaces while the hornet is in flight, creating such situations for a fraction of a second at a time. The insolation is absorbed more intensively in the furrows, owing to their shape. The picked up solar energy is now transmitted as electric charges from the furrows to the conduction stripes between abutting terraces, and thence to: (a) the rhodopsin pigment in the PP (the smaller moiety), or (b) the numerous cuticular layers, depending on the energy level of the picked up photons (the larger moiety), and (c) finally to the bacterial layer for storage in its walls. The latter region will be a p-type as compared to the energy stored in the layers of brown cuticle. The cuticle thus was found to contain many PPs but within the cuticle they are dispersed in contrast to the situation in the compound eye, where the many photoreceptors are concentrated.

Abdomen↗
PubMed1998

Micromorphology of the dorsal ocelli of the Oriental hornet.

The development of vision in animals throughout evolution has been reviewed by Sir Stewart Duke-Elder, whose survey of the sense of sight ranges from lowly Crustaceans to mammals and man. According to Duke-Elder each ocellus is formed by the "fusion of two or more ocelli, each with its own retina and pigment cup". This process of 'ocellation' probably occurred independently in a number of phyla. So far as Hymenoptera are concerned, at least in Bombus, only the median ocellus has retained any evidence of its 'dual' origin. In hornets, there are three ocelli which are organized on the dorsal part of the head and receive their innervation from the optical lobes that are located in the protocerebrum. Proceeding from the exterior to the interior, the ocelli are generally composed of a cornea, followed by corneogenic cell layers and then by a layer of sensory cells from which emerges the ocellar nerve. Thus, in wasps and hornets the ocelli consist of a group of visual cells beneath a common lens and they possibly accentuate the response to light stimuli that are perceived by the compound eyes. Recently, the ocelli have been ascribed roles in orientation and navigation. In honeybees the sensitivity of the ocelli to light at various wavelengths was compared with that of the compound eyes, and was found to be different, to wit: in the ocellus there were two peaks--one of UV light at a wavelength of 335-340 nm and the other of green light at 490 nm, whereas in compound eye the peaks were at 350 nm and 540 nm. From all the foregoing, it would seem that the role of the ocelli in insects in general and in hornets in particular is not yet sufficiently clear. The present study was undertaken to elucidate the structure of the ocelli in the Oriental hornet and possibly also their function.

Animals↗
PubMed1998

Are ciliary hair cells and photoreceptors components of a gravitic system of the hornet Vespa orientalis?

Social wasps, including the sub-family Vespinae, are social insects that build combs beneath the ground which are directed towards the gravitic pull of the earth, and this in dim light or complete darkness. On the inner side of the frons plate in social wasps there is a gravity sensing apparatus composed of static and dynamic nerve fibers, some of which connect between the frons plate and the brain. It is highly probable that the interaction between the fibers and the various structures in the head is responsible for the proprioceptive ability of hornets, including gravity detection. Ishay et al called the apparatus involved, the "Ishay Organ", and also reported the presence of (stereo) cilia on the inner side of the frons plate. The frons plate which bears the gravity organs functions as a photovoltaic system. Additionally there are throughout the cuticle, at intervals of several micrometers apart, distinct pores which are the outlets of peripheral photoreceptors. In the past various investigators have studied the ciliar structures of different insects mainly by TEM, but we have now studied the hair cells in hornets by FE-SEM, to obtain a complete 3-dimensional image of the various hair cell structures involved.

Animals↗
PubMed1996

Regeneration of guinea pig facial nerve: the effect of hypergravity.

Exposure to moderate hypergravity improves the regenerative capacity of sectioned guinea-pig facial nerve. The improvement in regeneration is tri-directional as follows: a) an average 1.7 fold increase in rate of regeneration in guinea pigs subjected to hypergravity; b) a 25% enhancement of facial muscle activity following the exposure to hypergravity; and c) improvement in the quality of regeneration from an esthetic standpoint. A good correlation was recorded between the histological structure of the severed nerve at the end of the regeneration and the clinical results.

Animals↗
PubMed1995

Thermo- and photoelectric current in hornet cuticle.

Thermoelectric and photoelectric currents were measured in the cuticle of hornets. The spontaneous current in the studied specimens ranged between 30-40 nAmp under conditions of darkness whereas under illumination the current drops to near zero. Upon warming up to 28-29 degrees C, the current rises to 50-200 nAmp but subsequently, after a while, it declines, regardless of whether the temperature is held steady, continues to rise or is lowered. In light, the current values are lower than in darkness and this under all conditions. When the specimen is charged with an electric current under fixed temperature, the current attains several microAmp in darkness but is usually less than that under illumination by about one order of magnitude. The capacitance values range between 1-7 mFarad both in light and in the dark. Possible mechanisms for creating this cuticular current and the changes which it undergoes under the various experimental conditions are discussed, and so also the properties of hornet cuticle as a semiconductor and possible applications of the described phenomena in everyday life of hornets.

Animals↗
PubMed1989

Geotropic sensitivity of hornets.

Oriental Hornet workers, Vespa orientalis (Hymenoptera: Vespinae) were measured for their responses to changes in the direction of the gravitational field and this under both static and kinetic (centrifugal) conditions. The hornets can build a comb (oriented towards the gravitational force) when their multifaceted eyes are covered. Building activity is undertaken in the dark as well as by hornets that had been blinded or had eclosed in the dark and had never seen any light. If the frons plate of hornets is damaged, there is no or little building, and the comb direction is distorted. Hornets eclosing from and developing in combs subjected to centrifugal spinning build combs whose direction is affected both by rotation and by the resultant of the gravitational and centrifugal forces.

Animals↗
PubMed1986

Geotropic sensitivity exhibited by single hornets: the influence of caste, age, light and temperature.

Hornet Vespa orientalis, Hymenoptera: Vespinae) workers, queens and males, aged 0-24 hours (i.e. juveniles) and 24 hours and more (i.e. adults) were tested for their responses to changes in the direction of the gravitational force while placed on a flat surface gradually tilted between 0.5 degree and 180 degrees. The tests were run on non-blind and blind hornets, at temperatures ranging between 18 degrees C and 35 degrees C, in daylight as well as in the dark. Up to 18 hours of age, negative phototaxis prevailed among the hornets, which displayed a clear preference for remaining in the dark regardless of the geotropic position. Between 18-24 hours of age, there was gradual appearance of a sensitivity to change in the geotropic position. Above 24 hr of age, the hornets became sensitive to changes in their declinations, with workers becoming sensitive at a 3-5 degrees declination, queens at 4-5 degrees and males at a declination of 8-l9 degrees from the horizontal. Hornet response takes the form of an upward climb, to the highest point of the test surface. Such response required a temperature exceeding 24.8-25 degrees C for workers, 23.2 degrees C for queens and 20.8-21 degrees C for males.

Age Factors↗
PubMed1982

Temperature dependence of the electrical resistivity of social wasp cuticle: a comparative study.

Resistance to electricity by social wasp cuticle is temperature dependent within the range of 1--40 degrees C. This was measured on the species Vespa orientalis (the Oriental hornet), Vespa crabro (the European hornet) and the wasp Dolichovespula saxonica. The resistance at first decreases with increased temperature, reaching a nadir which differs according to species, and then rises again up to 40 degrees C, the highest temperature tested. It is suggested that the cuticular changes in resistivity at different temperatures reflect the wasp's mechanism for detecting and regulating the temperature in their normal environment.

Animals↗