Mathematical analysis of the honeybee waggle dance.

A honeybee informs her nestmates of the location of a flower by doing a waggle dance. The waggle dance encodes both the direction of and distance to the flower from the hive. To reveal how the waggle dance benefits the colony, we created a Markov model of bee foraging behavior and performed simulation experiments by incorporating the biological parameters that we obtained from our own observations of real bees as well as from the literature. When two feeders were each placed 400 m away from the hive in different directions, a virtual colony in which honeybees danced and correctly transferred information (a normal, real bee colony) made significantly greater numbers of successful visits to the feeders compared to a colony with inaccurate information transfer. Howerer, when five feeders were each located 400 m from the hive, the inaccurate information transfer colony performed better than the normal colony. These results suggest that dancing's ability to communicate accurate information depends on the number of feeders. Furthermore, because non-dancing colonies always made significantly fewer visits than those two colonies, we concluded that dancing behavior is beneficial for hives' ability to visit food sources.

The dance of the honeybee: how do honeybees dance to transfer food information effectively?

A honeybee informs her nestmates of the location of a flower she has visited by a unique behavior called a "waggle dance." On a vertical comb, the direction of the waggle run relative to gravity indicates the direction to the food source relative to the sun in the field, and the duration of the waggle run indicates the distance to the food source. To determine the detailed biological features of the waggle dance, we observed worker honeybee behavior in the field. Video analysis showed that the bee does not dance in a single or random place in the hive but waggled several times in one place and then several times in another. It also showed that the information of the waggle dance contains a substantial margin of error. Angle and duration of waggle runs varied from run to run, with the range of +/-15 degrees and +/-15%, respectively, even in a series of waggle dances of a single individual. We also found that most dance followers that listen to the waggle dance left the dancer after one or two sessions of listening.

Sodium ascorbyl phosphate shows in vitro and in vivo efficacy in the prevention and treatment of acne vulgaris.

Acne vulgaris is the most common inflammatory skin disorder and jeopardizes seriously the facial impression of a person. Development of acne involves a complex relation among several causes. Treatment and prevention success can be archived by affecting the main contributors positively like Proprionibacterium acnes or lipid oxidation leading to inflammatory reactions and follicular keratinization. Vitamin C tends to break down in cosmetic formulations resulting in a brownish discoloration. Sodium ascorbyl phosphate (SAP) represents a stable precursor of vitamin C that ensures a constant delivery of vitamin C into the skin. We were able to show that 1% SAP has a strong antimicrobial effect with a log reduction of 5 after 8 h on P. acnes in a time-kill study. Further on in a human in vivo study with 20 subjects an SAP O/W formulation significantly prevents the UVA-induced sebum oxidation up to 40%. Finally, we performed an open in vivo study with 60 subjects with a 5% SAP lotion over 12 weeks. The efficacy ranked as excellent and good of SAP was 76.9%, which was superior compared with a widely prescribed acne treatment. In conclusion, these data show that SAP is efficient in the prevention and treatment of acne vulgaris. SAP can be used in a non-antibiotic and effective treatment or co-treatment of acne with no side effects, which makes it particularly attractive for cosmetic purposes.

Reconstruction of retinal horizontal cell responses by the ionic current model.

An ionic current model of the retinal horizontal cell is constructed. The horizontal cell models are interconnected by gap junctions to form a horizontal cell layer. The light response properties of the L-type horizontal cell are analyzed using this model. We demonstrate the functional role of each ionic current and the role of the feedback loop between cones and horizontal cells. The present study provides insight into the dynamic relationships between characteristics on the cellular level and on the multi-cellular level for producing the light response in horizontal cells.

Effect of alpha-tocopherol incorporation of glucose permeability and phase transition of lecithin liposomes.

Liposomes were prepared from dipalmitoyllecithin, dimyristoyllecithin, dioleoyllecithin, egg lecithin, and soybean lecithin, and the effects of incorporation of various quantities of alpha-tocopherol or its analogs on permeability of the liposomes to glucose were studied at various temperatures (4--40 degrees C). Results showed that increase in the quantity of alpha-tocopherol incorporated into dipalmitoyllecithin and dimyristoyllecithin liposomes lowered the transition temperature for marked release of glucose and also decreased the maximum rate of temperature-dependent permeability, alpha-Tocopherol also had similar but less marked effects on the permeability of dioleoyllecithin and egg lecithin liposomes, but little effect on those of soybean lecithin, which has a higher degree of unsaturation. In dipalmitoyllecithin liposomes phytol showed a similar effect of permeability to that of alpha-tocopherol, but phytanic acid caused a different pattern of temperature-dependent permeability. With analogs of alpha-tocopherol, the regulatory effect on permeability decreased with shortening and disappearance of the isoprenoid side chain. The significance of these observations is discussed in relation to the physiological functions of tocopherols in natural membranes.

[An inexpensive and flexible personal-computer-based system for controlling the multiple stimulus events in classical conditioning].

For the demand of biological discipline it is worth to develop a stimulus control system especially suitable for behavioral studies on learning and memory, in which the precise temporal control of the event sequence has been desired. We developed a flexible and inexpensive system based on IBM-PC for the classical conditioning of the marine mollusc. User can set a various temporal conditions with the data sheet on a display. It can be applicable in a wide range of conditions as well as in a lot of situations which require temporal control of multiple stimuli.

First principles multiplet calculations of the calcium L2,3 x-ray absorption spectra of CaO and CaF2.

First principles calculations are performed for the interpretation of the L2,3 x-ray absorption spectrum of calcium oxide and calcium fluoride. The first principles calculations are based on configuration interaction (CI) calculations using fully relativistic molecular spinors. The first principles results are compared to experimental data and also to calculations based on a semi-empirical crystal field multiplet model and also on a multichannel multiple scattering method. We show that the CI calculations show good agreement with experiment, both for bulk and for surface experiments. The remaining differences with experiment and between the theoretical models are discussed in detail.

Sequential modification of membrane currents with classical conditioning.

Pavlovian conditioning of the nudibranch mollusc Hermissenda crassicornis was previously shown to produce long-lasting reduction of two K+ currents measured across the Type B photoreceptor soma membrane (Alkon et al., 1982a; Alkon et al., 1985). Pavlovian conditioning of the rabbit was also shown to be followed by persistent K+ current reduction (Disterhoft et al., 1986). Here we report the first evidence that Ca2+ currents can also be modified by conditioning. The amplitude of the currents rather than their voltage-dependence remains reduced at least 1-2 d after conditioning (but not control procedures). Conditioning-induced changes of both K+ and Ca2+ currents increased as a function of training, the Ca2+ currents only changing substantially with greater than or equal to 250 trials. The later changes of the Ca2+ current may function to limit the magnitude of excitability increases due to associative learning.

Reconstruction of ionic currents in a molluscan photoreceptor.

Two-microelectrode voltage-clamp measurements were made to determine the kinetics and voltage dependence of ionic currents across the soma membrane of the Hermissenda type B photoreceptor. The voltage-dependent outward potassium currents, IA and ICa(2+)-K+, the inward voltage-dependent calcium current, ICa2+ and the light-induced current, IIgt, were then described with Hodgkin-Huxley-type equations. The fast-activating and inactivating potassium current, IA, was described by the equation; IA(t) = gA(max)(ma infinity[1-exp(-t/tau ma)])3 x (ha infinity [1-exp(-t/tau ha)] + exp(-t/tau ha)) (Vm-EK), where the parameters ma infinity, ha infinity, tau ma, and tau ha are functions of membrane potential, Vm, and ma infinity and ha infinity are steady-state activation and inactivation parameters. Similarly, the calcium-dependent outward potassium current, ICa(2+)-K+, was described by the equation, ICa(2+)-K+ (t) = gc(max)(mc infinity(VC)(1-exp[-t/tau mc (VC)]))pc (hc infinity(VC) [1-exp(-t/tau hc)] + exp(-t/tau hc(VC)])pc(VC-EK). In high external potassium, ICa(2+)-K+ could be measured in approximate isolation from other currents as a voltage-dependent inward tail current following a depolarizing command pulse from a holding potential of -60 mV. A voltage-dependent inward calcium current across the type B soma membrane, ICa2+, activated rapidly, showed little inactivation, and was described by the equation: ICa2+ = gCa(max) [1 + exp](-Vm-5)/7]-1 (Vm-ECa), where gCa(max) was 0.5 microS. The light-induced current with both fast and slow phases was described by: IIgt(t) = IIgt1 + IIgt2 + IIgt3, IIgti = gIgti [1-exp(- ton/tau mi)] exp(-ton/tau hi)(Vm-EIgti) (i = 1, 2). For i = 3, /Igt(t) = gigt3m33h3(Vm - Eigt3)exp(-ton/Ton) x exp(-tfoff/t Off). Based on these reconstructions of ionic currents, learning-induced enhancement of the long lasting depolarization (LLD) of the photoreceptor'slight response was shown to arise from progressive inactivation of /A, lca2+ -K+, and lCa2+.

Adult T-cell leukaemia with various abnormalities in endocrine and metabolic systems.

Adult T-cell leukaemia (ATL) is a unique type of T-cell malignancy closely associated with human T-cell leukaemia virus-1 (HTLV-1). Despite frequent descriptions of hypercalcaemia, cases accompanied by diabetes insipidus or syndrome of inappropriate secretion of anti-diuretic hormone (SIADH) in ATL patients have rarely been reported. We present an unusual case of ATL with various abnormalities in his endocrine and metabolic systems involving anterior pituitary function, thyroid function, lipid metabolism and Ca metabolism. Some of these abnormalities were considered to arise from infiltration or leukaemic cells into systemic organs after elimination of the above symptoms. Clinical and haematological data showing improvement following chemotherapy are also presented.