Molecular cloning and characterization of an invertebrate homologue of a neuropeptide Y receptor

Neuropeptide Y is an abundant and physiologically important peptide in vertebrates having effects on food intake, sexual behaviour, blood pressure and circadian rhythms. Neuropeptide Y homologues have been found in invertebrates, where they are very likely to play similar, important roles. Although five neuropeptide Y-receptor subtypes have been identified in mammals, none has been reported from invertebrates. Here we describe the cloning of a neuropeptide Y-receptor from the brain of the snail Lymnaea stagnalis. The identity of the receptor was deduced by expressing the neuropeptide Y-receptor-encoding cDNA in Chinese Hamster Ovary cells, which were subsequently challenged with size-fractionated Lymnaea brain extracts. An active peptide, selected on the basis of its ability to induce changes in cAMP levels, was purified to homogeneity, analysed by mass spectrometry and amino acid sequence determination, and turned out to be a Lymnaea homologue of neuropeptide Y.     

Lower begging responsiveness of host versus parasitic brown-headed cowbird (Molothrus ater) nestlings is related to species identity but not to early social experience.

The survival of young brood parasites depends critically on their many adaptations to exploit hosts. Parasitic survival is particularly related to competitive superiority for foster parental care whenever host young are not destroyed in parasitized nests. Brown-headed cowbirds (Molothrus ater) are generalist obligate parasites whose early social environments are unpredictable regarding host species and numbers of nestmates. Young avian brood parasites typically beg more intensively and loudly than foster siblings, but an untested prediction is that young parasites are also more likely to respond by begging to a wider variety of stimulus types. Avian vocalizations were used in a playback experiment to stimulate begging behavior in cowbird hosts. Compared with age-matched cowbird nestlings, hosts begged less frequently to acoustic stimuli, and lower begging responsiveness was irrespective of whether hosts had been reared in parasitized nests. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential expression of the estrogen-regulated proto-oncogenes c-fos, c-jun, and bcl-2 and of the tumor-suppressor p53 gene in the male mouse chronically infected with Taenia crassiceps cysticerci

Chronic infection with Taenia crassiceps cysticerci produces a 200-fold increase in serum estradiol levels in male mice. The aim of this study was to investigate the expression pattern of c-fos and c-jun, two estradiol-regulated genes, as well as that of p53 and bcl2 in the testes, spleen, and thymus of male mice infected with T. crassiceps cysticerci. In parasitized animals the c-fos mRNA content was significantly increased in all tissues studied, whereas the c-jun mRNA content was increased only in the thymus. The p53 mRNA content was markedly reduced in all tissues of the parasitized animals analyzed, whereas bcl-2 gene expression was abolished in the thymus. On the other hand, thymic cell analysis performed by flow cytometry showed a diminution in the content of CD3+, CD4+, and CD8+ subpopulations in the parasitized mice. Our results suggest that the increase in estradiol levels of the host should change the expression pattern of several genes that participate in apoptosis regulation in the thymus of male mice during chronic infection with T. crassiceps cysticerci.     

Nonmanipulative parasites in manipulated hosts: 'hitch-hikers' or simply 'lucky passengers'?

Manipulation of intermediate host behavior to favor parasitic transmission has been demonstrated in a wide of range of parasitic taxa. Recent advances in parasitology have suggested that nonmanipulative parasite species can obtain a high probability of transmission simply by infecting hosts already manipulated ('hitch-hiker' parasites). In this study, from a field collection of Gammarus aequicauda (Amphipoda, second intermediate host), we analyzed the ecological association between the manipulative trematode Microphallus papillorobustus and the 2 nonmanipulative trematodes Microphallus hoffmanni and Levinseniella tridigitata. Although these 2 nonmanipulative parasites should be a priori advantaged when infecting manipulated gammarids, there was no significant ecological association between parasite species. We discuss the possible reasons why these 2 nonmanipulative parasites are only 'lucky passengers' rather than 'hitch-hikers.'     

Unusual transmission of the liver fluke, Fasciola hepatica, by Lymnaea glabra or Planorbis leucostoma in France

Cases of fasciolosis in ruminants have been recorded in several French farms in the absence of Lymnaea truncatula, which is considered the only snail intermediate host in western Europe. These farms harbored other species of freshwater snails in large numbers (Lymnaea glabra, Physa acuta, or Planorbis leucostoma) and, in many cases, had cattle or sheep infected by another trematode (Paramphistomum daubneyi). These other freshwater snails may serve as intermediate hosts for F. hepatica due to a coexisting infection with P. daubneyi. We have demonstrated that L. glabra, either infected with F. hepatica alone or coinfected by P. daubneyi, was capable of developing a F. hepatica infection. A broader range of L. glabra size classes (up to 10 mm in height) were susceptible to infection if simultaneously infected with P. daubneyi. Planorbis leucostoma can only serve as an intermediate host for F. hepatica, if infected with P. daubneyi. Lastly, P. acuta smaller than 4 mm cannot serve as an intermediate host. These results may explain, in part, the maintenance of low-level F. hepatica infections in the absence of the normal intermediate host, L. truncatula.     

Transmitter identification in neurons involved in male copulation behavior in Lymnaea stagnalis

In this paper, we have mapped the cellular localization of various transmitters onto the central neurons which are involved in male copulation behavior in Lymnaea stagnalis, by combining retrograde tracing with immunocytochemistry and in situ hybridization. Evidence is provided that neurons which were backfilled from the penis nerve, the sole nerve to innervate the male copulatory organ, synthesize a multitude of neuropeptides (APGWamide, Lymnaea neuropeptide tyrosin [LNPY], conopressin, pedal peptide, SEEPLY, DEILSR, myomodulin, and Lymnaea inhibitory peptide [LIP]) as well as the classical neurotransmitter, serotonin. In the anterior lobe, the backfilled neurons mainly contain the tetrapeptide APGWamide and conopressin, and not LNPY or pedal peptide. The results suggest a central role in the regulation of copulation activity for the anterior lobe neurons that produce APGWamide and conopressin. Immunostainings of backfilled nervous systems revealed immunopositive axons originating from these neurons to form varicosities on the cell somata of neurons in the other clusters contributing to the innervation of the male sexual system. Neurons from the right parietal ganglion projecting into the penis nerve were electrophysiologically and morphologically identified by simultaneously recording from the cell body intracellularly and the penis nerve extracellularly and subsequently filling them with an anterograde tracer and subjecting them to immunocytochemistry. This method has provided links between morphology, physiology, and the transmitter contents of these neurons.     

Developmental plasticity of respiratory behavior in Lymnaea

The authors investigated the contribution of experience to development and maintenance of pulmonary respiration in Lymnaea stagnalis. Respiration in L. stagnalis is bimodal via both the skin and the lung. Rearing snails from eggs to adulthood while preventing lung respiration (differentially reared snails) showed that L. stagnalis can develop and survive without pulmonary respiration. These snails were able to open and close their pneumostome when given the opportunity as adults. However, quantitative aspects of their respiratory behavior were significantly altered. Prevention of pulmonary respiration in adult, normally reared snails also induced behavioral changes. Comparison of these changes with those in differentially reared snails revealed specific developmental effects, which were reversible. Thus, this is a suitable model system for studying questions related to behavioral plasticity.     

Identification of two novel diurnal genes by screening of a rat brain cDNA library

While the hypothalamus is fundamental for sleep and circadian regulation, the molecular mechanisms involved are poorly understood. We have used a differential gene expression technique to identify hypothalamic genes which have altered expression in rat sleep periods. Complex cDNA probes from rat hypothalami removed at Zeitgeber times 4 and 15 were hybridised to rat brain cDNA library girds. From 30 differentially expressed clones, six were further analysed and two were confirmed to exhibit increased expression at Zeitgeber time 4. A Northern blot hybridization of brain, heart, kidney, lung, testis and skin mRNA showed that both clones were brain specific. Therefore, we have identified two novel brain specific diurnally expressed hypothalamic genes. Both genes may have roles in sleep or circadian regulation.     

The use of synthetic peptides in the design of a consensus sequence vaccine for Pseudomonas aeruginosa

Based on the five-year population study of red voles Clethrionomys rutilus Pallas in southern West Siberia, we analysed the distribution of two predominating species of parasites (tapeworms Hymenolepis horrida and immature instars of ticks Ixodes persulcatus) in different demographic groups of the host, and seasonal changes of their incidence in the population. We assessed primary humoral immune response of the voles (splenic antibody-forming cells) to antigenic challenge (injection of sheep erythrocytes) in respect to occurrence of these parasites. It was revealed that infection with H. horrida significantly reduced the numbers of antibody-forming cells in immature summer-born voles. In contrast, immune responses in immature and mature voles, which where parasitized by I. persulcatus at the moment of capture, were significantly higher as compared to non-infected hosts. The possible mechanisms of influence of parasites on variability of immune reactions of voles in the population under study are discussed.     

Sub-Millimeter-Wave Spectroscopy of the Ar.H+3 and Ar.D+3 Ionic Complexes

The human papillomavirus type 11 (HPV-11) E7 protein can modulate host cell functions and is required for papilloma formation, but little is known concerning the regulation of its expression. This study was designed to determine whether the viral upstream regulatory region controlled expression from the E7 promoter and whether cis sequences differentially regulated E6 and E7 expression in laryngeal mucosal keratinocytes, the natural target cells for this virus. Reporter constructs were designed to study expression of the luciferase gene from the HPV-11 E7 promoter in its natural position downstream of a functional E6 promoter. E7 expression, like E6 expression, required upstream regulatory sequences. However, E7 expression was less sensitive to repression by viral E2 protein and to mutation of the Spl binding site adjacent to the E2 binding site. Moreover, there was differential sensitivity of the two promoters to mutation of the E6 TATA box, with E7 expression more affected than E6 expression. These findings show that, in the normal host cells for this virus, the E6 and E7 promoters can be independently regulated by the cis regulatory region adjacent to the E6 promoter.