蜜蜂嗅觉相关蛋白的研究进展

蜜蜂是一类营社会性生活的昆虫,蜂群中的蜂王、工蜂和雄蜂相互依存,各司其职,共同维持着群体严密有序的生活。其中,嗅觉系统在它们的生存和繁衍过程中起到重要的作用。昆虫对气味物质的感受过程是非常复杂的,需要有多种蛋白的参与。研究蜜蜂的化学感受机制可以帮助我们更深入地了解蜜蜂特有的行为及生物学特性。本文重点综述了与蜜蜂嗅觉相关的3种蛋白质的生化特性、分子结构、基因表达及其生理功能等方面的研究进展,以期为今后开展相关研究工作提供理论参考。     

Regulation of last reproduction steps in tsetse flies (Glossina: Diptera)

Summary

The regulation of ovulation and parturition, in the viviparous tsetse flies, constitutes a very precisely adjusted mechanism, Indeed the process of vitellogenesis takes places, in one oocyte only, during the incubation period when the larva is nourished in utero on milk produced by the mother. Neuropeptides, biogenic amines, neurotransmitters as well as ecdysone, and 20-hydroxyecdysone and also nervous outputs regulate ovulation and parturition. A model is proposed for the mechanisms controlling these processes.     

Copulatory behaviour of the tsetse flies Glossina morsitans and G.austeni

ABSTRACT. The copulatory behaviour of Glossina morsitans morsitans West. and G.austeni Newst. was analysed by filming. After a male and female engaged genitalia, the male performed a repertoire of five actions for 3–4 min: (1) 'rubbing' his metathoracic, tibiotarsal joint against the region of genital contact; (2) 'stroking' or hitting the female's head and thorax with his meso- and metathoracic legs; (3) 'wing flick' by moving his mesothoracic legs in a rowing motion whilst at the same time vibrating the wings as in normal flight; (4) 'wing vibration' with the wings vibrated in the closed position; (5) 'wings out' in which the wings are moved out to the flying position without any observable vibration. Each action was repeated many times, to give variable individual sequences, but declined in frequency exponentially over the first 3–4 min in copulo. The two species differed in the frequency of acts. Shortly before separation, a few hours later, actions 1 and 2 reappeared. Receptive females exhibited little overt behaviour except in the maintenance of a passive stance. Refractory females rejected a mating attempt by flexing the abdomen ventrally, vibrating their wings in the closed position, and pushing the male with meso- and metathoracic legs. The significance and possible functions of male behaviour are discussed in relation to mating in Glossina and other Diptera.     

Persistent courtship reduces male and female longevity in captive tsetse flies Glossina morsitans morsitans Westwood (Diptera: Glossinidae)

Where males can increase their mating success by harassing femalesuntil they accept copulation, harassing tactics can be expectedto evolve to a point where they have costs to the longevityof both sexes. By experimentally manipulating the sex ratioin captive groups of tsetse flies Glossina morsitans morsitans,we demonstrated that the longevity of females declines wheresex ratios are biased toward males, while the longevity of malesdeclines where the sex ratio is biased toward females. Neitherirradiation of males nor prevention of copulation by blockingor damaging the external male genitalia increased the longevityof females caged with them, suggesting that female longevitywas reduced by the physical aspects of male harassment ratherthan by components of the ejaculate     

Interactions between cattle and biting flies: effects on the feeding rate of tsetse

In Zimbabwe, studies were made of the effect of host behaviour on the feeding success of Glossina pallidipes Austen and G. morsitans morsitans Westwood (Diptera: Glossinidae) attracted to cattle of different age and sex. The mean feeding rates for male and female G. pallidipes attracted to oxen were 60% and 58%, respectively, compared to 33% and 53% for male and female G. m. morsitans. The feeding rate of G. pallidipes varied between oxen and was inversely correlated with a host's rate of defensive leg movements, which, in turn, was positively correlated with the density of Stomoxys spp. (Diptera: Muscidae) caught in the vicinity of the host. Tsetse were significantly less successful in feeding from young cattle. For G. pallidipes, the feeding rate on calves (<6 months) was 11%, whereas for male and female G. m. morsitans the rates were 12% and 20%, respectively. Significantly lower feeding rates were apparent for cattle aged up to 2 years, when the feeding rate for G. pallidipes (31%) was still significantly less than that on mature oxen (68%). Feeding rates for G. pallidipes on adult female cattle were lower than those on oxen (45% vs. 61%). The lower feeding rates in young animals were attributed to higher rates of defensive movements. The results suggest that higher rates of defensive activities by young cattle reduce the risk of them contracting trypanosomiasis.     

昆虫气味受体研究进展

嗅觉在昆虫的多种行为中发挥关键作用。气味分子与嗅觉神经元树突上气味受体的结合,参与了昆虫嗅觉识别的初始过程。昆虫的嗅觉神经元表达两类气味受体： 一是传统气味受体,该类受体同源性较低,在少部分嗅觉神经元中表达; 二是Or83b家族受体,该类受体不感受气味,在不同昆虫间较为保守且在大多数嗅觉神经元中表达。目前,对于单个传统气味受体的气味分子配体特异性所知甚少; 对于Or83b家族受体,一般认为其可能具有将传统气味受体运送至嗅觉神经元树突膜上的功能。此外,有一些实验证据不支持昆虫气味受体为G蛋白偶联受体的观点。     

Microsatellite diversities and gene flow in the tsetse fly,Glossina morsitans s.l

Tsetse flies occupy discontinuous habitats and gene flow among them needs to be investigated in anticipation of area-wide control programs. Genetic diversities were estimated at six microsatellite loci in seven Glossina morsitans submorsitans Newstead (Diptera: Glossinidae) populations and five microsatellite loci in six G. m. morsitans Westwood populations. Nei's unbiased diversities were 0.808 and 76 alleles in G. m. submorsitans and 0.727 and 55 alleles in G. m. morsitans. Diversities were less in three laboratory cultures. Matings were random within populations. Populations were highly differentiated genetically. Populations were strongly subdivided, as indicated by fixation indices (F(ST)) of 0.18 in G. m. morsitans and 0.17 in G. m. submorsitans. 35% of the genetic variance in G. m. submorsitans was attributed to differences between populations from The Gambia and Ethiopia. All available genetic evidence suggests that genetic drift is much greater than gene flow among G. morsitans s.l. populations.     

The optics of tsetse fly eyes in relation to their behaviour and ecology

Abstract The visual acuity of two species of tsetse flies, Glossina morsitans morsitans Westw. and Glossina pallidipes Aust., was investigated. Male G. morsitans eyes have an acute zone in the forward region, with large hexagonal lenses (mean minimum diameter, D=33, SE±0.7 μm), relatively small interommatidial angle (Δ(φ=1.08^o) and angular receptive field of individual ommatidia (Δp) of not less than 1.14^o. A narrow band of square lenses, with intermediate diameter and Δφ, merges with smaller hexagonal lenses in the periphery (24±0.7 μm), with relatively large interommatidial angle (Δφ=3.7^o) and small angular receptive field (Δp = c. 1.6^o). G.pallidipes eyes are similar, except that the lenses in the acute zone are larger than those of G.morsitans , in proportion to their larger body size. Female eyes are not significantly different from male eyes, except that they have a narrower region of binocular overlap (maximum for males = 24^o, for females = 18^o). The eye parameter (p=DΔφ) in the acute zone of male G.morsitans = 0.62, and in the peripheral zone = 1.56. These relatively high values are consistent with fast flight, visual detection of drift due to low wind speeds, mating chases and discrimination of cryptic host animals at high light intensities. The extended region of binocular overlap in males may serve as an early warning system of the approach of potential females. From our estimates, tsetse flies ought to be able to detect small objects against the sky c. 30 min before sunrise and after sunset, and to use their peripheral vision perhaps 15 min earlier and later than this.     

Reciprocal regulation of fat content and flight activity in male tsetse flies (Glossina palpalis)

Abstract. To disentangle cause and effect in previously observed relationships between fat content and flight activity in male tsetse ( Glossina spp.), three groups of flies were fed at different intervals to raise their fat content to different levels before their flight activity was recorded. The greater the mean daily blood intake, the higher the fat content and the greater the subsequent spontaneous flight activity, thereby using up almost all of the fat reserves before the next blood meal. It is proposed that although male flies would benefit from maximum food intake to permit maximum flight associated with mate-seeking, they do not in fact feed as often as possible either in the field or the laboratory. This is explicable if energy acquisition is constrained by an additional mortality risk associated with feeding.     

Olfactory and behavioural responses of tsetse flies, <Emphasis Type="Italic">Glossina</Emphasis> spp., to rumen metabolites

Herbivores provide tsetse flies with a blood meal, and both wild and domesticated ruminants dominate as hosts. As volatile metabolites from the rumen are regularly eructed with rumen gas, these products could serve tsetse flies during host searching. To test this, we first established that the odour of rumen fluid is attractive to hungry Glossina pallidipes in a wind tunnel. We then made antennogram recordings from three tsetse species (G. pallidipes morsitans group, G. fuscipes palpalis group and G. brevipalpis fusca group) coupled to gas chromatographic analysis of rumen fluid odour and of its acidic, mildly acidic and neutral fractions. This shows tsetse flies can detect terpenes, ketones, carboxylic acids, aliphatic aldehydes, sulphides, phenols and indoles from this biological substrate. A mixture of carboxylic acids at a ratio similar to that present in rumen fluid induced behavioural responses from G. pallidipes in the wind tunnel that were moderately better than the solvent control. The similarities in the sensory responses of the tsetse fly species to metabolites from ruminants demonstrated in this study testify to a contribution of habitat exploitation by these vertebrates in the Africa-wide distribution of tsetse.     

Evaluations of permethrin-impregnated clothing and three topical repellent formulations of deet against tsetse flies in Zambia

Permethrin-impregnated clothing and three topical repellent formulations of deet (diethyltoluamide) were field tested against natural populations of tsetse flies, mostly Glossina morsitans centralis Machado, in central Zambia. Volunteers wore different combinations of clothing impregnated with permethrin 0.125 mg ai/cm2 and repellents while riding in a vehicle that was driven slowly (4-6 km/h), with the windows and rear door open, through fly-infested areas. The mean rate of tsetse bites was about twenty per 75 min for unprotected people. The treatment combination of permethrin-impregnated clothing (blue cotton coveralls) and either of two controlled-release deet formulations on exposed skin of face and arms provided 91% mean protection, but this was not significantly better (P greater than 0.05) than wearing deet repellent alone (76-87% protection). No significant differences of protection were observed between the three repellent treatments, although the two controlled-release formulations (intended to be more persistent) were applied at approximately half the dosage of the standard 75% deet. Wearing permethrin-impregnated coveralls alone provided relatively poor protection (34%) for the untreated and exposed skin of head and hands. However, olive drab mesh jackets treated with permethrin reduced the tsetse biting rate by 75%.     

Abundance and distribution of the tsetse flies, Glossina austeni and G. brevipalpis, in different habitats in South Africa

The distribution and abundance of Glossina austeni Newstead and Glossina brevipalpis Newstead (Diptera: Glossinidae) were studied in the three main vegetation types in Zululand, KwaZulu-Natal, South Africa. During a period of 12 months, a trap transect consisting of 38 H-traps traversing the three vegetation types was monitored. The Index of Apparent Abundance (IAA) for G. brevipalpis was high in indigenous forest and open grassland but lower in exotic plantations. Glossina austeni, on the other hand, was captured mainly in or adjacent to indigenous forest. The seasonal trend in the IAA did not differ between vegetation types. The findings on the distribution of G. brevipalpis are in contrast with the historic records. Historically, this species was considered to be restricted to areas with a dense overhead canopy and high relative humidity. The repercussions of these findings for the epidemiology of livestock trypanosomiasis and the control of tsetse in Zululand are discussed.     

Ectopic expression of olfactory receptors and associated G-protein subunits in the head integument of the amphihaline migratory fish hilsa Tenualosa ilisha

The chemosensory nature of the tissue from the dorsal surface of the head (also termed sensory pad; SP) of the amphihaline diadromous fish hilsa Tenualosa ilisha was investigated for odorant receptor (OR), olfactory marker protein (OMP) and G-protein subunits (Gαs-olf, Gαq, Gαo, Gαi3) through immunolocalization and immunoblotting techniques. The immunolocalization of OR, OMP and G-protein subunits showed clear expression of these proteins in the tissues of the SP. Robust expressions of these proteins in the SP were detected with immunoblot analysis. The strong expression of these proteins in the SP indicates that the tissues from this area in riverine T. ilisha may play significant role in chemosensing and signalling through ectopic expression of olfactory receptor proteins which are otherwise reported in olfactory organs in vertebrates. Being migratory in nature, ectopic expression of these receptors in T. ilisha probably helps them to prevent damage to epidermal tissues of the SP, or they may also utilize them as a chemo and mechanosensory tool to optimize chemo-communications during migration.     

Dose responses of tsetse flies (Glossina) to carbon dioxide, acetone and octenol in the field

ABSTRACT Studies were conducted in Zimbabwe of the catch of Glossina pallidipes Austen from an electric net plus target baited with mixtures of acetone plus carbon dioxide or 1-octen-3-ol (octenol) plus carbon dioxide. For acetone dispensed alone at 5–50, 000 mg h^-1, ten-fold increments in the dose increased the catch 1.7 times. For carbon dioxide dispensed alone, dose increments from 12 to 1201 h^-1 doubled the catch, but the catch was not further increased by dispensing carbon dioxide at 600–1200 1 h^-1. For mixtures of these two odours, ten-fold increments in the dose of carbon dioxide between 12 and 12, 0001 h^-1 increased the catch c . 2.5 times if acetone was also dispensed at >50 mg h^-1; changes in the dose of acetone between 50 and 50 000 mg h^-1 did not affect the catch. The addition of octenol (0.05 mg h^-1) to carbon dioxide (12–12001 h^-1) doubled the catch. Ten-fold increments in the dose of octenol between 0.05 and 5 mg h^-1 did not increase the catch significantly and the catch was independent of changes in the dose of carbon dioxide between 120 and 12001 h^-1. The behavioural basis of the dose-response curves was investigated using an incomplete ring of electric nets to assess the flight orientation of tsetse in different odours. Upwind flight was not elicited by acetone or octenol alone, or by carbon dioxide unless it was at very high doses, however, mixtures of carbon dioxide with acetone or octenol elicited upwind flight. It is suggested that the attractiveness of mixtures of acetone and carbon dioxide is a function of the region of overlap of these two odours at above threshold concentration. Acetone and octenol on their own appear to increase the responsiveness of flies to visual cues.     

Flight responses of tsetse flies (Glossina) to octenol and acetone vapour in a wind-tunnel

Abstract. Female Glossina morsitans morsitans Westwood were video-recorded in a wind-tunnel as they entered, in crosswind flight, a broad plume of either octenol or acetone (two components of ox odour). Both odours produced upwind turning responses (in-flight anemotaxis) to a range of concentrations, with thresholds at around 10^-8mg1^-l for octenol and 10^-6mg1^-1 for acetone. Kinetic responses were unaffected by octenol at low concentrations, but flight speed was significantly reduced and sinuosity (^om^-1) and angular velocity (^os^-1) significantly increased by concentrations at or above those in ox breath; for acetone, these effects were apparent but inconsistently related to concentration. It is concluded that octenol and acetone vapour are used by tsetse flies to locate hosts by upwind anemotaxis, probably combined with kinetic responses. The behavioural basis for the 'repellency' of high octenol concentrations in the field is discussed in the context of the virtual loss of upwind anemotaxis to octenol at the highest concentration tested in the tunnel (30 × ox breath).     

The activation of resting tsetse flies (Glossina) in response to visual and olfactory stimuli in the field

ABSTRACT Studies were conducted in Zimbabwe of the responses of Glossina morsitans morsitans Westwood and Glossina pallidipes Austen resting in a refuge to various host stimuli. Tsetse took off in response to 100% ox odour, 0.08% carbon dioxide or a visual stimulus consisting of a 0.75 × 0.75 m black target placed c . 5 m from the refuge moving at 4^o s^-1, but the level of response was low with only 35%, 19% and 29% responding, respectively. Tsetse did not take off in response to any one of 25% ox odour, 0.8% carbon dioxide, acetone (3 μg 1^-1) or octenol (0.03 μg 1^-1). In the absence of any host stimuli, flies emerged from the refuge later on hotter days (35–37^oC) than on cooler days (32–34.5^oC). Male G.pallidipes emerging later in the afternoon contained significantly more haematin than those emerging relatively earlier. There were no significant differences between the responses of G.m. morsitans and G.pallidipes. It is suggested that the initial activation of resting flies is primarily mediated through endogenous, rather than host, stimuli.     

Developmental expression of odorant‐binding proteins and chemosensory proteins in the embryos of Locusta migratoria

We have investigated the development of chemosensilla and the secretion of odorant‐binding proteins (OBPs) and chemosensory proteins (CSPs) in the embryo of Locusta migratoria manilensis. We first report the changes of each sensillum in embryo just preceding hatch in detail and show that different sensilla have different developmental processes. Trichogen cells are first involved in forming the structure of pegs, and then, after retraction, they start secreting OBPs and CSPs in the sensillar lymph. The synthesis of LmigOBP1 starts during the embryogenesis about 0.5 h preceding hatching, specifically in sensilla trichodea and basiconica of the antenna. LmigOBP2, instead, was only found in the outer sensillum lymph (oSl) of sensilla chaetica of the antenna, while we could not detect LmigOBP3 in any type of sensilla of the antenna. The ontogenesis of CSPs in the embryos is similar to that of OBPs. Expression of CSPI homolog in Locusta migratoria is detected using the antiserum raised against SgreCSPI. CSPI is specifically expressed in the outer sensillum lymph of sensilla chaetica of the antenna, and anti‐LmigCSPII dose not label any sensilla of the embryos. These data indicate that in locusts, OBPs and CSPs follow different temporal expression patterns, and also that OBPs are expressed in different types of sensilla. © 2009 Wiley Periodicals, Inc.