A change of sensitivity threshold of <Emphasis Type="Italic">Apis mellifera</Emphasis> to action of pathogen at different periods of starvation

The work studies thresholds of sensitivity in the honeybee Apis mellifera in connection with action of different periods of starvation on biochemical and cellular parameters of protective reactions. Intraspecies differences are shown during additional action of a bacterial preparation at the physiological level. An importance of the hidden (latent) phase for the insects is evaluated in manifestation of the general adaptive syndrome, which precedes the phase of anxiety development. The intraspecies peculiarities of response of protective systems in the honeybee consist not only in the activity level of physiological processes, but also in the rate of overcoming the sensitivity threshold to pathogen.     

Synergistic activation of insect cAMP-dependent protein kinase A (type II) by cyclicAMP and cyclicGMP

The high cGMP sensitivity of cAMP-dependent protein kinase A (type II) (PKAII) from invertebrates led to the hypothesis that cGMP directly activates PKAII under physiological conditions. We tested this idea using PKAII holoenzyme purified from the honeybee brain in an assay with short stimulation times. In the presence of very low cAMP concentrations, we found a synergistic increase in PKAII activation by physiological cGMP concentrations. Cloning honeybee regulatory subunit RII and phylogenetic comparison of the two cyclic nucleotide-binding sites of RII reveal a high relation of domain A of insect RII with cGMP-binding domains of cGMP-dependent protein kinases.     

Physiological effects of hypoxia in developing and adult honeybees <Emphasis Type="Italic">Apis mellifera</Emphasis> L.

The effect of hypoxia on activity of metabolism was studied in developing and adult honeybees. The feedback was established between the O₂ deficit in the gas medium and its consumption by honeybees. An elevation of temperature within the limits of vital diapason for development of honeybees activated the O₂ consumption regardless of the hypoxia level. A prolonged action of hypoxia on the honeybee physiological state was revealed. There was shown the existence of convergent similarity between the effect of O₂ deficit on honeybees and on homoiothermal animals.     

Cold-induced lipid phase transitions

The structural organization of biological membranes is largely determined by the weak interactions existing between their components and between these components and their aqueous environment. These interactions are particularly sensitive to changes in temperature and hydration. The factors influencing membrane lipid phase behaviour are briefly reviewed and used to develop a phase-separation model describing the response of biological membranes to stress. The factors affecting the interaction of cryoprotectants with membrane lipids are explored and their role in the stabilization of membrane organization at low temperatures discussed. It is suggested that the basis of their protective action lies in an ability to preserve the balance of interactions between membrane components at low temperatures at a level similar to that existing under physiological conditions.     

一种新的蜜蜂细菌性幼虫病病原的分离鉴定

2005年早春,在浙江部分地区出现了一种严重的蜜蜂细菌性幼虫病,该病导致蜜蜂幼虫颜色发黄,失去光泽;严重时幼虫死亡腐烂。从10批发病死亡幼虫样品中,分离得到并保存了5类纯培养物。通过蜂群接种试验和实验室人工培养的幼虫接种,确定L2菌株能引起与自然发病相似的症状,且能从接种发病的幼虫上再次分离到相同菌株,证明L2菌株是该蜜蜂细菌性幼虫病的致病菌。进一步对分离到的该致病菌从发病特征、病原形态学、生理生化特性、16SrRNA序列等方面进行了分析鉴定,结果显示:该菌株属于肠球菌属的屎肠球菌(Enterococcusfaecium),不是目前报道的任何一种已知蜜蜂细菌性幼虫病的病原。     

Selection for varroatosis resistance in honeybees

The parasitic mite Varroa jacobsoni is a major problem for beekeeping worldwide. It can be controlled efficiently with a variety of ocaracides. However, Robin F.A. Moritz argues that, owing to the risk of honey contamination and the costs involved with continuous treatment of honeybee (Apis mellifera L.) colonies, there is a pressing need to find alternative ways of varroatosis control. A variety of physiological and behavioural traits of the honeybee are known to control efficiently the development and spread of V. jacobsoni infestation. Breeding of a varroatosis-resistant honeybee seems possible and selection could offer swift results if one capitalizes on the male haploid population structure of the honeybee.     

Diurnal and Seasonal Changes in Thermal Preference of Single,Isolated Bees and Small Groups of Bees (Apis mellifera L.)

The aim of the present study was: to compare thermoregulatory behaviour of single honeybee workers and groups of 3–15 bees over their annual activity period and to check out whether the annual fluctuations of ambient temperature selection are correlated with phases of the colony development. Thermal behaviour of both single workers and groups of bees was recorded, using a video camera, in a thermal gradient system. Thermal preferences of the insects were tested seasonally in spring (May/June), summer (July/August) and autumn (September–November). Both single bees and small groups of bees changed their thermal behaviour in daily cycle. The season of the year had distinct effect on temperature preferences of both single honeybee workers or small groups of bees. In single honeybee workers the lowest ambient temperatures were preferred in late spring (the swarming phase) while the highest temperatures were selected during the summer (the colony growing phase). There were significant seasonal changes in ambient temperature selected by groups of honeybee workers. Groups of honeybee workers tended to prefer the lowest temperatures in late spring and the highest temperatures were selected during the summer. The day-night differences exhibited by small groups of bees in our experiments are likely to represent behavioural responses of the honeybee colony. In our experiments we proved an influence of the season of the year on the honeybees’ thermal behaviour, which might be connected with seasonal shifts of temperature regulated by the honeybee colony.     

Exposure to sublethal doses of fipronil and thiacloprid highly increases mortality of honeybees previously infected by Nosema ceranae

BACKGROUND: The honeybee, Apis mellifera, is undergoing a worldwide decline whose origin is still in debate. Studies performed for twenty years suggest that this decline may involve both infectious diseases and exposure to pesticides. Joint action of pathogens and chemicals are known to threaten several organisms but the combined effects of these stressors were poorly investigated in honeybees. Our study was designed to explore the effect of Nosema ceranae infection on honeybee sensitivity to sublethal doses of the insecticides fipronil and thiacloprid. METHODOLOGY/FINDING: Five days after their emergence, honeybees were divided in 6 experimental groups: (i) uninfected controls, (ii) infected with N. ceranae, (iii) uninfected and exposed to fipronil, (iv) uninfected and exposed to thiacloprid, (v) infected with N. ceranae and exposed 10 days post-infection (p.i.) to fipronil, and (vi) infected with N. ceranae and exposed 10 days p.i. to thiacloprid. Honeybee mortality and insecticide consumption were analyzed daily and the intestinal spore content was evaluated 20 days after infection. A significant increase in honeybee mortality was observed when N. ceranae-infected honeybees were exposed to sublethal doses of insecticides. Surprisingly, exposures to fipronil and thiacloprid had opposite effects on microsporidian spore production. Analysis of the honeybee detoxification system 10 days p.i. showed that N. ceranae infection induced an increase in glutathione-S-transferase activity in midgut and fat body but not in 7-ethoxycoumarin-O-deethylase activity. CONCLUSIONS/SIGNIFICANCE: After exposure to sublethal doses of fipronil or thiacloprid a higher mortality was observed in N. ceranae-infected honeybees than in uninfected ones. The synergistic effect of N. ceranae and insecticide on honeybee mortality, however, did not appear strongly linked to a decrease of the insect detoxification system. These data support the hypothesis that the combination of the increasing prevalence of N. ceranae with high pesticide content in beehives may contribute to colony depopulation.     

Effect of stretching on the action potentials of the human and rabbit ventricular myocardium

The effect of stretching from L0 to Lmax on the electrical activity was studied on human myocardial preparations from patients with heart disease and on strips of rabbit ventricular myocardium. Muscular deformation was shown to decrease the amplitude and velocity of depolarization in slow action potentials. The action potentials (AP) possessing a fast depolarization phase were not sensitive to physiological stretching. Antiarrhythmic drugs--ethmozin (2 X 10(-5) M) and ethacizin (2 X 10(-6) M)--caused a decrease in the rate of AP depolarization, thus increasing AP sensitivity to deformation. It is suggested that stretching under the action of ethmozin and ethacizin reduced cardiomyocyte excitability due to suppression of slow Ca-current.     

Steroid control of gonadotropin secretion

Current knowledge about the mechanism and site of action of estradiol (E2) and progesterone (P) during the menstrual cycle and the physiological role of androgens is reviewed. In normal women, the positive feedback effect of E2 at the pituitary level is the principal event of the follicular phase inducing the LH surge. P, by its negative feedback at the hypothalamic level and by its positive feedback at the pituitary level regulates GnRH and LH secretion during the luteal phase. Androgens do not directly play a role in gonadotropin regulation.     

Exogenous and endogenous fluctuations of thermoregulatory activity in the honeybee

Thermovision and thermometric methods were used to study temperature variations in honeybee nests and in aggregations of honeybees isolated from their families. Endogenous and exogenous circadian rhythms of thermoregulatory activity and their physiological mechanisms were revealed. The magnitude of changes in this activity in response to ambient temperature decreased from the beginning to the end of wintering, which was due to the existence of a genetically determined self-regulation program in honeybees. The improvement of this program in the course of the species evolution contributed to transformation of a honeybee family into a reproducible biological unit.     

蜜蜂毒主要过敏原磷脂酶A_2研究概述

本文综述了国内外蜜蜂毒主要过敏原磷脂酶Ａ_２的研究进展,主要包括一般的蛋白质特性、作用机制、免疫学及生物学作用等。     

Defensins in the honeybee antiinfectious protection

Specific conditions of the honeybee life honeybee life require the presence of effective mechanisms of antiinfectious protection whose one of the most important components are defensins—the family of antimicrobial peptides. In the honeybee, defensins are present in the form of two different peptides—defensin 1 and 2 that are similar between each other only by 55.8%. Defensin 1 synthesized in salivary glands plays an important role in social immunity, whereas defensin 2 synthesized by cells of fat body and lymph is an important factor in the system of the honeybee individual immunity. Defensins are inducible, are controlled by interaction of Toll and Imd signal pathways and have a large specter of antimicrobial action.     

蜜蜂蜂王浆主蛋白(MRJPs)的研究进展

蜜蜂的蜂王浆主蛋白具有为蜂王和幼虫提供营养、影响蜂群社会行为及调节个体生理机能等作用,作为蜂王浆的主要成分对其他机体也可产生多方面的生物学功能。因此,近年来蜂王浆主蛋白的相关研究备受关注。本文针对蜂王浆主蛋白的发现、种类、功能、系统进化及其基因表达情况进行了系统综述。     

Amtyr1: characterization of a gene from honeybee (Apis mellifera) brain encoding a functional tyramine receptor

Biogenic amine receptors are involved in the regulation and modulation of various physiological and behavioral processes in both vertebrates and invertebrates. We have cloned a member of this gene family from the CNS of the honeybee, Apis mellifera. The deduced amino acid sequence is homologous to tyramine receptors cloned from Locusta migratoria and Drosophila melanogaster as well as to an octopamine receptor cloned from Heliothis virescens. Functional properties of the honeybee receptor were studied in stably transfected human embryonic kidney 293 cells. Tyramine reduced forskolin-induced cyclic AMP production in a dose-dependent manner with an EC50 of approximately 130 nM. A similar effect of tyramine was observed in membrane homogenates of honeybee brains. Octopamine also reduced cyclic AMP production in the transfected cell line but was both less potent (EC50 of approximately 3 microM) and less efficacious than tyramine. Receptor-encoding mRNA has a wide-spread distribution in the brain and subesophageal ganglion of the honeybee, suggesting that this tyramine receptor is involved in sensory signal processing as well as in higher-order brain functions.     

Out of the blue: the spectral sensitivity of hummingbird hawkmoths

The European hummingbird hawkmoth Macroglossum stellatarum is a diurnal nectar forager like the honeybee, and we expect similarities in their sensory ecology. Using behavioural tests and electroretinograms (ERGs), we studied the spectral sensitivity of M. stellatarum. By measuring ERGs in the dark-adapted eye and after adaptation to green light, we determined that M. stellatarum has ultraviolet (UV), blue and green receptors maximally sensitive at 349, 440 and 521 nm, and confirmed that green receptors are most frequent in the retina. To determine the behavioural spectral sensitivity (action spectrum) of foraging moths, we trained animals to associate a disk illuminated with spectral light, with a food reward, and a dark disk with no reward. While the spectral positions of sensitivity maxima found in behavioural tests agree with model predictions based on the ERG data, the sensitivity to blue light was 30 times higher than expected. This is different from the honeybee but similar to earlier findings in the crepuscular hawkmoth Manduca sexta. It may indicate that the action spectrum of foraging hawkmoths does not represent their general sensory capacity. We suggest that the elevated sensitivity to blue light is related to the innate preference of hawkmoths for blue flowers.     

蜜蜂级型分化相关生理因子研究进展

蜜蜂Apis melliferaL.是典型的社会性昆虫,蜂群内蜂王和工蜂的级型分化现象吸引了众多研究者的高度关注。蜜蜂级型分化是一个极为复杂的生长发育调节过程,许多重要生理因子参与其中,包括保幼激素、蜕皮激素、胰岛素/胰岛素类似物信号通路等。本文概述了蜜蜂级型分化相关生理因子研究进展:保幼激素决定着蜜蜂级型发育的轨迹并能阻止卵巢发育过程中细胞的程序性死亡;蜕皮激素协同保幼激素发挥调节作用;蜜蜂蜂王与工蜂的躯体大小及相关器官大小的级型特异性差异与胰岛素/胰岛素类似物信号通路密切相关。此外,本文还介绍了蜜蜂级型分化模型,该模型系统描述了上述各生理因子对级型分化的综合作用。     

Signal and regulatory effects of methylglyoxal in eukaryotic cells (review)

Methylglyoxal (MG) is one of the physiological glucose metabolites formed in living organisms. The data on the influence of MG on different internal systems of eukaryotic cells, including the central signaling pathways, are been discussed in the review. The central signaling pathways are stress-activated and sensitive to the action of reactive oxygen species. Integration of the literary data and authors’ results has allowed the conclusion that MG action on cells is multidirectional and is determined by its concentration and the physiological state of the cell. The cellular reaction upon increasing MG concentrations has a phase pattern and can be described by the hormesis concept. It has been hypothesized that MG participates in the formation of the braking regulatory circuit, which modulates the sensitivity of hypothalamus neurons to glucose. It is concluded that MG has a possible role in the functioning of the great biological clock. We propose that the data discussed in this review allow methylglyoxal to be considered a molecule with signal and regulatory functions.     

Hygropreference and brood care in the honeybee (Apis mellifera)

Terrestrial organisms need to limit evaporation from their bodies in order to maintain a homeostatic water balance. Owing to a large surface to volume ratio, arthropods are particularly susceptible to desiccation and have evolved behavioural and physiological mechanisms to conserve water. In social insects, water balance is also affected by the interactions between nestmates and by the architecture of the nest. For honeybees, humidity is particularly important for the brood because it affects the hatching success of eggs and because, unlike ants, honeybees cannot relocate their brood to parts of the nest with more favourable humidity. To advance the understanding of the water economy in honeybee nests, we investigated whether workers exhibit a hygropreference when exposed to a gradient of 24-90% relative humidity (RH) and whether the expression of this preference and their behaviour is affected by the presence of brood. The results show that young honeybee workers in the absence of brood exhibit a weak hygropreference for approximately 75% RH. When brood is present the expression of this preference is further weakened, suggesting that workers tend to the brood by distributing evenly in the gradient. In addition, fanning behaviour is shown to be triggered by an increase in humidity above the preferred level but not by a decrease. Our results suggest that humidity in honeybee colonies is actively controlled by workers.     

Triazines facilitate neurotransmitter release of synaptic terminals located in hearts of frog (Rana ridibunda) and honeybee (Apis mellifera) and in the ventral nerve cord of a beetle (Tenebrio molitor)

Three triazine herbicides, atrazine, simazine and metribuzine, and some of their major metabolites (cyanuric acid and 6-azauracil) were investigated for their action on synaptic terminals using three different isolated tissue preparations from the atria of the frog, Rana ridibunda, the heart of the honeybee, Apis mellifera macedonica, and the ventral nerve cord of the beetle, Tenebrio molitor. The results indicate that triazines facilitate the release of neurotransmitters from nerve terminals, as already reported for the mammalian central nervous system. The no observed effect concentration, the maximum concentration of the herbicide diluted in the saline that has no effect on the physiological properties of the isolated tissue, was estimated for each individual preparation. According to their relative potency, the three triazines tested can be ranked as follows: atrazine (cyanuric acid), simazine>metribuzine (6-azauracil). The action of these compounds on the cholinergic (amphibians, insects), adrenergic (amphibian) and octopaminergic (insects) synaptic terminals is discussed.