Behavioral and electroantennogram analysis of olfactory stimulation inlozenge: ADrosophila mutant lacking antennal basiconic sensilla (Diptera: Drosophilidae)

Two alleles of the mutant lozengeof Drosophila melanogaster, lzand lz³,lack basiconic sensilla on the antennal funiculus. To elucidate the role of these sensilla for the perception of food odors, we studied the locomotor behavior and the electroantennogram (EAG) activity of lozenge flies in response to olfactory stimuli. The significance of basiconic sensilla on the maxillary palps was assessed by testing the locomotion of flies surgically deprived of their palps. The behavioral data suggest that antennal and maxillary basiconic sensilla may be important receptors for short chain alcohols and organic acids but less crucial receptors for acetates, aldehydes, and ketones. In agreement with this interpretation, EAG responses to alcohols (but not to esters) were found to be markedly lower in lozengethan in the wild type.     

Morphological and functional heterogeneity in olfactory perception between antennae and maxillary palps in the pumpkin fruit fly,Bactrocera depressa

The morphology and ultrastructure of the olfactory sensilla on the antennae and maxillary palps were investigated through scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and their responses to five volatile compounds were measured using electroantenogram (EAG) and electropalpogram (EPG) techniques in the pumpkin fruit fly, Bactrocera depressa (Shiraki; Diptera: Tephritidae). Male and female B. depressa displayed distinct morphological types of olfactory sensilla in the antennae and maxillary palps, with predominant populations of trichoid, basiconic, and coeloconic sensilla. Basiconic sensilla, the most abundant type of olfactory sensilla in the antennae, could be further classified into two different types. In contrast, the maxillary palps exhibited predominant populations of a single type of curved basiconic sensilla. High‐resolution SEM observation revealed the presence of multiple nanoscale wall‐pores on the cuticular surface of trichoid and basiconic sensilla, indicating that their primary function is olfactory. In contrast, coeloconic sensilla displayed several longitudinal grooves around the sensillum peg. The TEM observation of individual antennal olfactory sensilla indicates that the basiconic sensilla are thin‐walled, while the trichoid sensilla are thick‐walled. The profile of EAG responses of male B. depressa was different from their EPG response profile, indicating that the olfactory function of maxillary palps is different from that of antennae in this species. The structural and functional variation in the olfactory sensilla between antennae and maxillary palps suggests that each plays an independent role in the perception of olfactory signals in B. depressa.     

Distribution of chemo- and mechanoreceptors on the antennae and maxillae of Busseola fusca larvae

The stem borer Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is a major pest of maize, Zea mays L., and sorghum, Sorghum bicolor (L.) Moench (both Poaceae), in sub-Saharan Africa. Like in many other lepidopteran insects, the success of B. fusca in recognizing and colonizing a limited variety of plants is based on the interaction between its sensory systems and the physicochemical characteristics of its immediate environment. The sensilla on the maxillary galeae of B. fusca larvae are typical of Lepidoptera and comprise two uniporous styloconic sensilla, which are contact chemoreceptors, three basiconic sensilla, and two aporous sensilla chaetica. The maxillary palp is two-segmented and has eight small basiconic sensilla at the tip, which were also found to be gustatory. The antennae of B. fusca larvae are short and simple. The sensilla of the antenna are composed of two aporous sensilla chaetica, three multiporous cone-shaped basiconic sensilla, three small basiconic sensilla, and one aporous styloconic sensillum. The basiconic sensillum located on the third antennal segment displayed a contact chemoreception response. The other basiconic sensilla did not show any action potential activity in tip-recording tests. The significant and positive dose–response curve obtained for the antennal basiconic sensillum with sucrose indicated for the first time the presence of gustatory chemoreceptors on the antennae of a lepidopteran larva.     

Sequential functioning of Sym-13 and Sym-31 , two genes affecting symbiosome development in root nodules of pea ( Pisum sativum L.)

Two Fix⁻ mutants of pea (Pisum sativum L.) which are unable to fix molecular nitrogen, E135f (sym-13) and Sprint-2Fix⁻ (sym-31), were crossed to create the doubly homozygous recessive line, named RBT (sym-13, sym-31). The ultrastructural organization of nodules of the RBT line was compared with that of each of the two parental mutant lines and with the original wild-type genotypes of the cultivars Sparkle and Sprint-2. It was shown that the RBT line is similar to the mutant line Sprint-2Fix⁻ in having abnormal symbiosome composition and bacteroids with relatively undifferentiated morphology. Because the phenotypic manifestation of the sym-31 mutant allele suppresses the phenotypic manifestation of the sym-13 mutant allele, it is concluded that the function of the gene Sym-31 (which is mutated in the Sprint-2Fix⁻ line) is necessary at an earlier stage of symbiosome development than the gene Sym-13 (which is mutant in the E135f line). Received: 28 October 1996 / Accepted: 22 January 1997     

Olfactory physiology in the Drosophila antenna and maxillary palp: acj6 Distinguishes two classes of odorant pathways

This article provides characterization of the electrical response to odorants in the Drosophila antenna and provides physiological evidence that a second organ, the maxillary palp, also has olfactory function in Drosophila. The acj6 mutation, previously isolated by virtue of defective olfactory behavior, affects olfactory physiology in the maxillary palp as well as in the antenna. Interestingly, abnormal chemosensory jump 6 (acj6) reduces response in the maxillary palp to all odorants tested except benzaldehyde (odor of almond), as if response to benzaldehyde is mediated through a different type of odorant pathway from the other odorants. In other experiments, different parts of the antenna are shown to differ with respect to odorant sensitivity. Evidence is also provided that antennal response to odorants varies with age, and that odorants differ in their age dependence. © 1992 John Wiley & Sons, Inc.     

Morphological and ultrastructural characterization of olfactory sensilla in Drosophila suzukii: Scanning and transmission electron microscopy

Drosophila suzukii is a serious horticultural and quarantine pest, damaging various berry crops. Although the active use of olfactory communication in D. suzukii is well-known, their olfactory sensory system has not been comprehensively reported. Therefore, the present study was carried out to understand the morphology, distribution and ultrastructure of olfactory sensilla present in the antennae and maxillary palps of D. suzukii, through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The olfactory sensilla on the antennae of D. suzukii in both sexes could be classified into three major morphological types, basiconic, trichoid and coeloconic sensilla, according to their shapes. The antennal basiconic sensilla were further divided into three subtypes and the antennal trichoid sensilla into two subtypes, respectively, according to the size of individual sensillum. In contrast to the antennal olfactory sensilla showing diverse morphology, basiconic sensilla was the only type of olfactory sensilla in the maxillary palps of D. suzukii. The basiconic sensilla in the maxillary palps could be further classified into three subtypes, based on their size. Our SEM and TEM observations indicated that multiple nanoscale pores are present on the surface of all types of olfactory sensilla in the antennae and maxillary palps, except coeloconic sensilla. The difference in the morphological types and the distribution of olfactory sensilla suggests that their olfactory functions are different between antennae and maxillary palps in D. suzukii. The results of this study provide useful information for further studies to determine the function of olfactory sensilla in D. suzukii and to understand their chemical communication system.     

Electrophysiological responses to sucrose from a gustatory sensillum on the larval maxillary palp of the spruce budworm,Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae)

The tip of the maxillary palp in the spruce budworm and other lepidoptera larvae contains a cluster of eight basiconic sensilla. Except for a few electrophysiological recordings from the entire group of these sensilla, no information is available on the response characteristics of any individual one. Using a compound microscope at 320x magnification, with a long working-distance objective, it has been possible to view individual sensilla and to record electrical responses from three of these to some gustatory stimuli in preliminary tests. One of them, sensillum (L1), contains a sugar-sensitive neuron whose responses to a range of sucrose concentrations are reported here. The physiological characteristics of this neuron differ from those of the known sugar-sensitive neuron in the lateral styloconic sensillum on the galea of these same insects. Input of chemosensory information about the same gustatory stimulus by more than one neuron in different mouthpart sensilla is discussed in relation to the feeding habits of the spruce budworm.     

七星瓢虫唇须感器分布和统计特征的雌雄差异

应用扫描电镜观察七星瓢虫Coccinella septempunctata的唇须和附节,以便确认在感应农药残留时起主要作用的化学感受器。研究证明分布在下颚须上的感器类型包括两种锥形感器（兼有机械感受器和化学感受器的功能）和一种钟形感器。同时本文首次报道了对这些感器精确的形态测量,明确了其性二型性。对下颚须的测量表明其左右末节的长度差异与七星瓢虫的性别之间有明显的相关性。文中还记述了下唇须上一种新的钟形感器,其在每个下唇须上的数量大约为12～17个。经测量这些机械感受器的平均直径为2.4 μm。早期研究中所记述的锥形感器被证实是下唇须上仅有的化学感应器,并且首次证明这些锥形感器的数量与性别相关,雄性平均为18个,雌性平均为16个。附节上也存在性别差异： 第2跗节跗垫的宽度在雄性中是从后向前逐渐增大,而在雌性中刚好相反。本文还就这些差异的意义以及新发现感器的功能进行了讨论。     

The effect of endurance exercise at moderate altitude on serum lipid peroxidation and antioxidative functions in humans

We investigated the effect of training and racing at moderate altitude (MA) on oxidative stress by assessment of serum diene conjugation (DC) and serum antioxidant potential (TRAP). Nine male top level skiers were studied during a national race (20–30 km) at sea level (SL). Thereafter, the athletes trained for 2 weeks at MA, after which they participated in a 20–30 km race at MA. Venous blood samples were taken before and after the race. The DC, indicating early events of lipid peroxi dation, did not change during the race at SL (16 850 vs 15 900 ΔAbsorbance · l⁻¹) or at MA (19 870 vs. 20 630 ΔAbs · l⁻¹). At MA serum DC was higher than at SL both before (25%) and after (30%) the race, the postrace difference being statistically significant (P < 0.05). The TRAP increased during the race at MA (from 1387 to 1943 μmol · 1⁻¹, P  =  0.016), but not at SL (1713 vs 1582 μmol · l⁻¹). These observations would suggest that the level of oxidative stress might be greater during living, training and racing at MA (higher DC levels). Increased TRAP during the race at MA may indicate that the physiological adaptation to extreme acute oxidative stress was altered. The physiological significance of this observation remains to be investigated. Accepted: 18 October 1996