Host preference of cotton fleahopper, Pseudatomoscelis seriatus (Reuter) is not labile to geographic origin and prior experience

Several phytophagous insects exhibit distinct preference for their host plants. In widely distributed generalist insects, host preference can be influenced by geographic variation in host plant distribution and abundance as well as by prior experience. We have studied host preference of the cotton fleahopper, Pseudatomoscelis seriatus (Reuter), a pest of cotton in Texas and other neighboring states, by measuring olfactory orientation to horsemint (Monarda punctata L.) and cotton (Gossypium hirsutum L.). Horsemint is one of the primary, native, wild hosts of cotton fleahopper during late-spring and early summer in Texas, and it is commonly believed to be the main source of this pest in cotton. Although the abundance of horsemint, and therefore the fleahopper exposure to it, varies geographically, cotton fleahopper's preference for this native host-plant is maintained across two ecoregions in Texas, TX High Plains (Lubbock area) and Brazos Valley (College Station area). Similarly, preference for horsemint was retained regardless of prior experience with cotton throughout all the life stages of the insect. This fixed preference of cotton fleahopper to horsemint could be because of their ancestral insect-plant interaction, better fitness of cotton fleahopper on horsemint, and relatively low abundance of horsemint compared with cotton. Information gained from this study could be used to implement cultural control practices such as trap cropping, to develop attractants to monitor this pest, or both.     

Peptidomics of the Agriculturally Damaging Larval Stage of the Cabbage Root Fly Delia radicum (Diptera: Anthomyiidae)

The larvae of the cabbage root fly induce serious damage to cultivated crops of the family Brassicaceae. We here report the biochemical characterisation of neuropeptides from the central nervous system and neurohemal organs, as well as regulatory peptides from enteroendocrine midgut cells of the cabbage maggot. By LC-MALDI-TOF/TOF and chemical labelling with 4-sulfophenyl isothiocyanate, 38 peptides could be identified, representing major insect peptide families: allatostatin A, allatostatin C, FMRFamide-like peptides, kinin, CAPA peptides, pyrokinins, sNPF, myosuppressin, corazonin, SIFamide, sulfakinins, tachykinins, NPLP1-peptides, adipokinetic hormone and CCHamide 1. We also report a new peptide (Yamide) which appears to be homolog to an amidated eclosion hormone-associated peptide in several Drosophila species. Immunocytochemical characterisation of the distribution of several classes of peptide-immunoreactive neurons and enteroendocrine cells shows a very similar but not identical peptide distribution to Drosophila. Since peptides regulate many vital physiological and behavioural processes such as moulting or feeding, our data may initiate the pharmacological testing and development of new specific peptide-based protection methods against the cabbage root fly and its larva.     

Myotropic activity and immunolocalization of selected neuropeptides of the burying beetle Nicrophorus vespilloides (Coleoptera: Silphidae)

Burying beetles (Nicrophorus sp.) are necrophagous insects with developed parental care. Genome of Nicrophorus vespilloides has been recently sequenced, which makes them interesting model organism in behavioral ecology. However, we know very little about their physiology, including the functioning of their neuroendocrine system. In this study, one of the physiological activities of proctolin, myosuppressin (Nieve? MS), myoinhibitory peptide (Trica-MIP-5) and the short neuropeptide F (Nicve-sNPF) in N. vespilloides have been investigated. The tested neuropeptides were myoactive on N. vespilloides hindgut. After application of the proctolin increased hindgut contraction frequency was observed (EC50 value was 5.47 x 10-8 mol/L). The other tested neuropeptides led to inhibition of N. vespilloides hindgut contractions (Nicve-MS: IC50 = 5.20 x 10~5 mol/L;Trica-MIP-5: IC50 = 5.95 x 10-6 mol/L;Nicvc-sNPF: IC50 = 4.08 x 10-5 mol/L). Moreover, the tested neuropeptides were immunolocalized in the nervous system of N. vespilloides. Neurons containing sNPF and MIP in brain and ventral nerve cord (VNC) were identified. Proctolin-immunolabeled neurons only in VNC were observed. Moreover, MIP-immunolabeled varicosities and fibers in retrocerebral complex were observed. In addition, our results have been supplemented with alignments of amino acid sequences of these neuropeptides in beetle species. This alignment analysis clearly showed amino acid sequence similarities between neuropeptides. Moreover, this allowed to deduce amino acid sequence of N. vespilloides proctolin (RYLPTa), Nicve-MS (QDVDHVFLRFa) and six isoforms ofNicve-MIP (Nicve-MIP-1一 DWNRNLHSWa;Nicve-MIP-2—AWQNLQGGWa;Nicve-MIP-3—AWQNLQGGWa;Nicve-MlP-4—AWKNLNNAGWa;Nicve-MIP-5—SEWGNFRGSWa;Nicve-MIP-6— DPAWTNLKGIWa;and Nicve-sNPF—SGRSPSLRLRFa).     

Comparative peptidomics of four related hemipteran species: pyrokinins, myosuppressin, corazonin, adipokinetic hormone, sNPF, and periviscerokinins

We performed the first comprehensive peptidomic analysis of neurohormones from hemipteran insects by analyzing the neuropeptides of two major neurohemal organs, namely the corpora cardiaca and abdominal perisympathetic organs. For the experiments we selected four related species of polyphagous stinkbugs (Pentatomidae), three of which are known to attack several important food crops. Peptide sequences were identified by MALDI-TOF mass spectrometry; tandem fragmentation of myosuppressin, sNPF, CAPA-periviscerokinins and pyrokinins revealed novel sequences not known from other insects so far. Most Leu/Ile and Glu/Lys ambiguities could be solved by either specific side-chain fragmentations or on-plate acetylation experiments. The identification of the specific sequences provides a solid basis for forthcoming pharmacological tests to study the neuroendocrine system of these pest insects. However, it should be mentioned in this context that the sequences of the peptides from different stinkbugs are likely not representative of Hemiptera in general. The forthcoming release of the genome from the reduviid Rhodnius prolixus will provide sufficient data to clear this point.     

Effect of the red imported fire ant on cotton aphid population density and predation of bollworm and beet armyworm eggs

The effects of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), on cotton aphid, Aphis gossypii Glover, populations and its predation of bollworm, Helicoverpa zea (Boddie), and beet armyworm, Spodoptera exigua (Hübner), (both Lepidoptera: Noctuidae) eggs were evaluated in cotton under field conditions during 2001 and 2002 in central and northern Texas. In central Texas, cotton aphid populations were approximately 5.5 times greater and predation of sentinel bollworm eggs 2 times greater in the presence of S. invicta versus in its absence, although aphid populations did not reach economic levels. Most predation of beet armyworm egg masses, measured via direct nocturnal observations, was due to S. invicta (68%) and cotton fleahopper, Pseudatomoscelis seriatus (Reuter) (21%), where S. invicta was present, and by the mite Abrolophus sp. (52%), spiders (13%), and minute pirate bug (Orius sp.) (13%) where S. invicta was absent. Predation of sentinel bollworm eggs and beet armyworm egg masses was approximately 1.5 and 4.1 times greater, respectively, in the presence of S. invicta versus in their absence. In the presence of S. invicta, the relative frequencies of minute pirate bug and cotton fleahopper were higher, and of S. invicta and native ants lower in beat bucket samples compared with their relative frequencies in nocturnal observations of predation upon beet armyworm egg masses. In the absence of S. invicta seven of eight predators sampled were similarly represented in beat bucket samples and nocturnal observations of beet armyworm egg mass predation, whereas minute pirate bug occurred at a higher frequency in beat bucket samples relative to nocturnal observations. These observations suggested that the relative frequencies of minute pirate bug, cotton fleahopper, S. invicta and native ants in beat bucket samples do not closely reflect the frequency with which these predators prey on noctuid eggs. Overall, the results of this study show that although S. invicta may promote aphid populations early in the growing season, it is an important predator of bollworm and beet armyworm eggs later in the season.     

Insect neuropeptides: Structures,chemical modifications and potential for insect control

Insect neuropeptides are involved in almost all physiological processes in insects, such as diuresis, ecdysis, pheromone biosynthesis and control of muscle activity. Thus, these small peptide hormones and their receptors are promising targets for a novel generation of selective and non-neurotoxic insecticides. However, due to poor bioavailability, pharmacokinetics and short half-life the peptides themselves cannot be used as insect control agents. The past two decades have seen an increase in research into the discovery of non-peptide small molecules that function as mimics for neuropeptides. This review presents an overview on structure–activity studies, conformational analyses and peptidomimetic modifications of selected insect neuropeptides with a special potential for application in pest control.     

Diapausing Colorado potato beetles are devoid of short neuropeptide F I and II

An extract of head ganglia and retrocerebral complexes of nondiapausing and diapausing Leptinotarsa decemlineata was prepared to characterize regulatory neuropeptides involved in adult diapause by using a differential peptidomics approach. To reduce sample complexity, both extracts were roughly separated by means of an identical chromatographic step. MALDI-TOF MS led to the identification of proctolin, an adipokinetic hormone, and short neuropeptide F I and II in the extract of nondiapausing beetles. In combination with nano-ESI-Q-TOF MS(2) evidence was found for the presence of three pyrokinins, the first to be identified in a coleopteran species. Pyrokinins, involved in the induction of embryonic diapause in Bombyx mori, were present in both physiological conditions suggesting that they are of minor importance in the regulation of adult diapause in the Colorado potato beetle. A striking difference, detected by the differential peptidomics approach, between both neuropeptide profiles was the absence of ions corresponding to the short neuropeptide F (sNPF) related peptides, also known as Led-NPF-I and -II, in the extract of diapausing animals. Therefore, we postulate that "short NPFs" are involved in the regulation of adult diapause, displayed by the Colorado potato beetle.     

Toward a consensus nomenclature for insect neuropeptides and peptide hormones

The nomenclature currently in use for insect neuropeptide and peptide hormone families is reviewed and suggestions are made as to how it can be rationalized. Based upon this review, a number of conventions are advanced as a guide to a more rationale nomenclature. The scheme that is put forward builds upon the binomial nomenclature scheme proposed by Raina and Gäde in 1988 [100], when just over 20 insect neuropeptides had been identified. Known neuropeptides and peptide hormones are assigned to 32 structurally distinct families, frequently with overlapping functions. The names given to these families are those that are currently in use, and describe a biological function, homology to known invertebrate/vertebrate peptides, or a conserved structural motif. Interspecific isoforms are identified using a five-letter code to indicate genus and species names, and intraspecific isoforms are identified by Roman or Arabic numerals, with the latter used to signify the order in which sequences are encoded on a prepropeptide. The proposed scheme is sufficiently flexible to allow the incorporation of novel peptides, and could be extended to other arthropods and non-arthropod invertebrates.     

高通量质谱法用于小鼠器官内源性肽的鉴定

内源性肽以细胞因子、生长激素、激素肽等形式在人体的内分泌、神经、细胞生长和生殖各个领域发挥功能。神经肽是一种内源性肽,与痛觉、睡眠、情绪、学习与记忆等生理活动相关,不但存在于脑部神经细胞,也存在于其他体液和器官内并发挥重要作用。目前对器官内源性肽的研究仍不足,尤其是其中的神经肽。文中应用液质联用串联质谱高通量鉴定胰腺、心脏、肝脏和肾脏中内源性肽的分布以及神经肽的种类。鉴定结果显示,在肝脏中内源性肽和神经肽的数目最多,而胰腺中最少;所鉴定到的内源性肽具有器官特异性,在4个器官中分别呈现不同的动态分布;4个器官中神经肽的LPV(最长肽变异体)数目差异较大,而且基因家族的分布也各不相同,比如胰腺中的神经肽多属于Glucagon家族,心脏中的神经肽分别属于ACBD7、Granins、PEBP等几个家族。鉴定结果将为疾病的机制研究和治疗药物的研发提供参考。     

Skin peptide and cDNA profiling of Australian anurans: genus and species identification and evolutionary trends

Host defense peptides of 35 species of Australian frogs from the hylids Cyclorana and Litoria, and the myobatrachids Crinia, Limnodynastes and Uperoleia have been identified. The biological activities of the majority of these peptides have been determined and include hormones, neuropeptides, opioids, immunomodulators, membrane active peptides [including antimicrobial, anticancer, antiviral (enveloped viruses like HIV and Herpes) and antifungal peptides], neuronal nitric oxide synthase inhibitors, pheromones and individual peptides with other specific activities. The host defense peptide skin profile can be diagnostic at both the species and higher taxonomic levels; for example, species of Crinia, Litoria and Uperoleia each produce quite different types of peptides. Species of Cyclorana and Limnodynastes are more difficult to characterize by skin peptides alone: species of both genera produce similar peptides with no apparent activity. The skin peptide profiles of frogs from the genera Crinia, Litoria and Uperoleia may be used together with morphological and cognate methods, to differentiate between sub-species and even different population clusters of the same species. Nucleotide sequencing of cDNAs of precursors (pre-pro peptides) of bioactive peptides from the skin glands of various species of the genus Litoria show that the majority of these peptides originated from a single ancestor gene before the break away of Australia from Gondwana. The exceptions are the caerulein neuropeptides {e.g. caerulein [pEQDY(SO₃H)TGWMDF(NH₂)]} which have a different origin to that of other Litoria peptides. Disulfide containing peptides from skin glands of species of Crinia show a different evolutionary route to peptides from species of Litoria.     

Neutral endopeptidase is expressed on the follicular granulosa cells of rabbit ovaries

Neutral endopeptidase (NEP) is a zinc metallopeptidase ubiquitously distributed in various tissues in mammals. This peptidase is involved in the post-secretory metabolism of various neuropeptides and peptide hormones in vivo, such as enkephalins, bradykinin, atrial natriuretic peptide, substance P and endothelins. In this paper we show that NEP is expressed in ovaries as a 110-kDa glycosylated integral membrane protein with enzymatic properties similar to those of the kidney protein. Using immunohistochemistry, we localize the peptidase in the granulosa cells of follicles at all stages of maturation, with the exception of atretic follicles. We also observe immunoreactive staining in the epithelia that lines the blood vessels in the medulla and the surface of the ovary. The co-localization of NEP and bioactive peptides known to be physiological substrates of NEP in other tissues suggests an important role for this protein in processes such as follicle maturation, ovulation, and/or regulation of ovarian blood flow, by modulating the physiological function of these peptides.     

New insect order Mantophasmatodea: species differentiation by mass fingerprints of peptide hormones?

We analysed peptide hormones of South African species of the recently described insect order Mantophasmatodea. Mass spectrometric techniques made it possible to analyse minute amounts of material stored in different neurohemal organs of single specimens. The methodological approach underlying this application is described and resulted in the first completely sequenced peptide hormones of the Mantophasmatodea, namely adipokinetic hormone, leucomyosuppressin, and a novel member of the periviscerokinins. The extensive peptide screening revealed a surprisingly clear differentation of species by peptide mass fingerprints. This is the first successful attempt to catalogue neuropeptides of insects for systematic/taxonomic purposes. In total, 14 of 32 peptides differed across species. Moreover, the data presented here show a hierarchy in the tendency for modifications among the different peptide hormones.     

Visualization of neuropeptides in paraffin-embedded tissue sections of the central nervous system in the decapod crustacean, Penaeus monodon, by imaging mass spectrometry

The distributions of neuropeptides in paraffin-embedded tissue sections (PETS) of the eyestalk, brain, and thoracic ganglia of the shrimp Penaeus monodon were visualized by imaging mass spectrometry (IMS). Peptide signals were obtained from PETS without affecting morphological features. Twenty-nine neuropeptides comprising members of FMRFamide, SIFamides, crustacean hyperglycaemic hormone, orcokinin-related peptides, tachykinin-related peptides, and allatostatin A were detected and visualized. Among these findings we first identified tachykinin-related peptide as a novel neuropeptide in this shrimp species. We found that these neuropeptides were distributed at specific areas in the three neural organs. In addition, 28 peptide sequences derived from 4 types of constitutive proteins, including actin, histones, arginine kinase, and cyclophilin A were also detected. All peptide sequences were verified by liquid chromatography-tandem mass spectrometry. The use of IMS on acetic acid-treated PETS enabled us to identify peptides and obtain their specific localizations in correlation with the undisturbed histological structure of the tissue samples.     

A comparative review of short and long neuropeptide F signaling in invertebrates: Any similarities to vertebrate neuropeptide Y signaling?

Neuropeptides referred to as neuropeptide F (NPF) and short neuropeptide F (sNPF) have been identified in numerous invertebrate species. Sequence information has expanded tremendously due to recent genome sequencing and EST projects. Analysis of sequences of the peptides and prepropeptides strongly suggest that NPFs and sNPFs are not closely related. However, the NPFs are likely to be ancestrally related to the vertebrate family of neuropeptide Y (NPY) peptides. Peptide diversification may have been accomplished by different mechanisms in NPFs and sNPFs; in the former by gene duplications followed by diversification and in the sNPFs by internal duplications resulting in paracopies of peptides. We discuss the distribution and functions of NPFs and their receptors in several model invertebrates. Signaling with sNPF, however, has been investigated mainly in insects, especially in Drosophila. Both in invertebrates and in mammals NPF/NPY play roles in feeding, metabolism, reproduction and stress responses. Several other NPF functions have been studied in Drosophila that may be shared with mammals. In Drosophila sNPFs are widely distributed in numerous neurons of the CNS and some gut endocrines and their functions may be truly pleiotropic. Peptide distribution and experiments suggest roles of sNPF in feeding and growth, stress responses, modulation of locomotion and olfactory inputs, hormone release, as well as learning and memory. Available data indicate that NPF and sNPF signaling systems are distinct and not likely to play redundant roles.     

Discovery of multiple neuropeptide families in the phylum Platyhelminthes

Available evidence shows that short amidated neuropeptides are widespread and have important functions within the nervous systems of all flatworms (phylum Platyhelminthes) examined, and could therefore represent a starting point for new lead drug compounds with which to combat parasitic helminth infections. However, only a handful of these peptides have been characterised, the rigorous exploration of the flatworm peptide signalling repertoire having been hindered by the dearth of flatworm genomic data. Through searches of both expressed sequence tags and genomic resources using the basic local alignment search tool (BLAST), we describe 96 neuropeptides on 60 precursors from 10 flatworm species. Most of these (51 predicted peptides on 14 precursors) are novel and are apparently restricted to flatworms; the remainder comprise nine recognised peptide families including FMRFamide-like (FLPs), neuropeptide F (NPF)-like, myomodulin-like, buccalin-like and neuropeptide FF (NPFF)-like peptides; notably, the latter have only previously been reported in vertebrates. Selected peptides were localised immunocytochemically to the Schistosoma mansoni nervous system. We also describe several novel flatworm NPFs with structural features characteristic of the vertebrate neuropeptide Y (NPY) superfamily, previously unreported characteristics which support the common ancestry of flatworm NPFs with the NPY-superfamily. Our dataset provides a springboard for investigation of the functional biology and therapeutic potential of neuropeptides in flatworms, simultaneously launching flatworm neurobiology into the post-genomic era.