Determination of Affinity and Activity of Ligands at the Human Neuropeptide Y Y4 Receptor by Flow Cytometry and Aequorin Luminescence

Fluorescence-labeled neuropeptide Y (NPY) has been used in flow cytometric binding assays for the determination of affinity constants of NPY Y₁, Y₂, and Y₅ receptor ligands. Because the binding of fluorescent NPY is insufficient for competition studies at the human Y₄ receptor (hY₄R), we replaced Glu-4 in hPP with Lys for the derivatization with cyanine-5. Because cy5-[K⁴]hPP has high affinity (K_d 5.6 nM) to the hY₄R, it was used as a probe in a flow cytometric binding assay. Specific binding of cy5-[K⁴]hPP to hY₄R was visualized by confocal microscopy. The hY₄R, the chimeric G protein G_qi5 and mitochondrially targeted apoaequorin were stably coexpressed in CHO cells. Aequorin luminescence was quantified in a microplate reader and by a CCD camera. By application of these methods 3-cyclohexyl-N-[(3-1H-imidazol-4-ylpropylamino)(imino)methyl]propanamide (UR-AK49) was discovered as the first nonpeptidic Y₄R antagonist (pK_i 4.17), a lead to be optimized in terms of potency and selectivity.     

Karyotype analysis and polyploidy in Palaua and a comparison with its sister group Fuertesimalva (Malvaceae)

Palaua (Malveae, Malvaceae) comprises 15 species endemic to the hyperarid coastal desert of Chile and Peru. So far, chromosome counts have been known for two diploid species (2n = 2x = 10) only. Here we report new chromosome numbers for 12 species of Palaua and four of its sister group Fuertesimalva. Karyotypes including 4',6'-diamidino-2-phenylindole dihydrochloride (DAPI)/chromomycin (CMA3) fluorescent banding are presented for selected species representative of each of the main clades of Palaua. An important finding is the discovery of polyploids in one exclusively tetraploid species (P. Trisepald) and four species with mixed diploid and tetraploid cytorypes (P. Dissecta, P. Mollendoensis, P. Moschata, and P. Tomentosa). The diploid and tetraploid karyotypes are all unimodal, symmetrical and show one or two pairs of satellite chromosomes with their associated CMA+/DAPI-band depending on the cytotype. For some of the tetraploids an autopolyploid origin is suggested.     

Relative air humidity influences the function of the tarsal chemoreceptor cells of the cherry fruit fly (Rhagoletis cerasi)

ABSTRACT. Electrophysiological recordings from the tarsal D-sensilla of mature, 5–7-day-old female European cherry fruit fly ( Rhagoletis cerasi L.) revealed that a large proportion of sensilla showed no sensory activity in response to stimulation with the oviposition deterring pheromone ('ODP') or sucrose. In contrast, good recordings were obtained from almost all sensilla in freshly emerged, 1-day-old flies. Ageing, nutritional state and contamination were excluded as possible major factors influencing the responsiveness of the D-sensilla. The study of the variability in responsiveness of the sensilla of 1-day-old flies among different tarsomers, among tarsi of the same individual and among individuals, revealed that the major source of variability was among individuals.
Individual flies were also affected by the humidity in the holding cages: relative air humidity of less then 75% for 4–6 days was shown to reduce the number of D-sensilla giving recordings with a good signal-to-noise ratio. The D-sensilla on the most distal tarsomers were affected most by the reduced (30–55% r. h.) air humidity. Flies which had contact with plant leaves showed less reduction in responsiveness at low air humidity (40% r. h.) then flies without leaf contact.     

Seed preference and energy intake of Goldfinches Carduelis carduelis in the breeding season

The food of a population of Europeans Goldfinches breeding in Orchards was studied. More than 5% of the total foodstuff consumed was met by the seeds of seven food plants. Water, lipid, carbohydrate and protein content was determined from 20 different plants which Goldfinches used during the breeding season in order to calculate energy content. The energy of fresh seeds varied from 1.88 kJ/g in Tussilago farfara to 12.14 kJ/g in Dactylis glomerata. The dependence of the rate of energy intake (profitability) on the pecking rate and the size (weight) of the seeds was calculated. The profitability of various seeds is in agreement with the relative number of birds using them. Calculation of the feeding time that a Goldfinch needs during daylight hours, if it feeds only on a particular plant, indicates that there are several foods that cannot fill the energy demands of the bird during the breeding season. These are eaten only if others with a high energy content are not available. Thus food selection in Goldfinches depends, apart from availability, on seed profitability. The oxygen consumption of a male Goldfinch was significantly higher when the animal was feeding on seed heads of Tussilago farfara and Taraxacum officinale than when it fed on loose dry seeds, and so, different feeding techniques have to be taken into account in calculating net energy gain.     

Systematics of the mealybug tribe Xenococcini (Hemiptera: Coccoidea: Pseudococcidae), with a discussion of trophobiotic associations with Acropyga Roger ants

The mealybug tribe Xenococcini (Hemiptera: Pseudococcidae) comprises three genera, Eumyrmococcus Silvestri, Neochavesia Williams & Granara de Willink and Xenococcus Silvestri, trophobiotically associated with ants of the genus Acropyga Roger (Hymenoptera: Formicidae). Alate Acropyga queens vertically transmit trophobionts by carrying them along on the nuptial flight, a unique behaviour termed trophophoresy. Xenococcine mealybugs have never been collected without ant associates, and putatively only associate with Acropyga. Xenococcine mealybugs are characterized by the absence of dorsal ostioles, presence of distally cup‐shaped circuli and a female pupal instar rather than a third feeding instar. The phylogeny of this tribe is derived for the first time using morphological data from adult females (53 characters) through Bayesian inference and maximum parsimony methods. Monophyly of the clade is strongly supported and a discussion of their taxonomy is included. The Neotropical genus Neochavesia was recovered as monophyletic. Eumyrmococcus, as previously defined, was recovered as paraphyletic, and thus two species are transferred to Xenococcus: Xenococcus kinomurai (Williams & Terayama) comb.n. and Xenococcus neoguineensis (Williams) comb.n . Two species groups are recognized within Eumyrmococcus: the Eumyrmococcus scorpioides species group, restricted to the eastern Mediterranean and Afrotropics, and the Eumyrmococcus smithii species group, restricted to the Orient and Indo‐Australasia. Six new species are described: Eumyrmococcus adornocapillus sp.n. from Australia; Eumyrmococcus sarnati sp.n. from Fiji; Eumyrmococcus ordinotersus sp.n. and Xenococcus baryglobosus sp.n. from the Solomon Islands; Neochavesia cephalonodus sp.n. from French Guiana; and Neochavesia linealuma sp.n. from Guyana. The systematics and biology of the xenococcine mealybugs is discussed in the context of obligate ant symbiosis.