Neurotensin-like Peptides in the CNS of Lampreys: Chromatographic Characterization and Immunohistochemical Localization with Reference to Aminergic Markers

Neurotensin (NT)-like peptides in the CNS of the lamprey Lampetra fluviatilis were studied by radioimmunoassay (C-terminal specific NT antiserum), reverse-phase HPLC and immunohistochemistry. Multiple peaks of NT-immunoreactive (-ir) material were observed upon HPLC, of which a major peak eluted in the position of bovine NT. Immunofluorescence histochemistry showed that a monoclonal antibody recognizing the N-terminal (1 - 11) fragment of NT, as well as two polyclonal NT antisera labelled a large number of cell bodies in the periventricular area of hypothalamus, including the postinfundibular commissural nucleus and the ventral and dorsal hypothalamic nuclei. Additional groups of NT-ir cells were observed in the preoptic nucleus, the postoptic commissural nucleus, the mesencephalic tegmentum (L.fluviatilis), and in the spinal cord (L.fluviatilis and Ichtyomyzon unicuspis). Dense NT-ir fibre plexuses were present in the caudal hypothalamus, corpus striatum, ventral mesencephalon, and in the dorsal horn and lateral margin of the spinal cord. At the ultrastructural level the lateral spinal margin showed NT-ir terminal structures, which in most cases were not associated with synaptic specializations, although occasional synaptic contacts with unlabelled elements were found. The relation between NT-ir and monoamine-containing cells was examined with immunofluorescence double-staining, using antisera to tyrosine hydroxylase (TH), 5-hydroxytryptamine (5-HT), and histamine respectively. In the periventricular nuclei of hypothalamus numerous TH-, 5-HT-, as well as histamine-ir cells were located in close association with NT-ir cells, but none of the aminergic markers could be detected within NT-ir neurons. The chemical properties as well as the anatomical distribution of lamprey NT-like peptides show several similarities with those present in mammals, suggesting that NT-containing neuronal systems in the CNS developed early in vertebrate phylogeny.     

图们江日本七鳃鳗异尖线虫蚴感染情况调查

调查自海洋回游于图们江的日本七鳃鳗感染异尖线虫蚴情况,结果本次剖检的210尾中感染异尖线虫蚴者35尾(16.67％),感染强度1～4条。雌性47尾中22尾感染(46.81％),雄性163尾中58尾(35.58％)感染,雌雄相比有非常显著性差异(P<0.01),可能与雌性溯河回游及入江产卵需频繁索饵积累营养有关,寄生部位以肌肉最多(54.17％),再依次为生殖腺、腹腔、肠壁、肝脏等。对日本七鳃鳗异尖线虫蚴调查在国内外为首次。图们江为异尖线虫的新分布区,日本七鳃鳗为异尖线虫的一种新中间宿主。提出了北太平洋为异尖线虫病自然疫源地,异尖线虫病为海洋自然疫源疾病。     

微小按蚊种团酯酶同工酶比较研究

应用聚丙烯酰胺凝胶电泳 ( PAGE)技术比较分析了 3种 (微小按蚊、乌头按蚊、溪流按蚊 )雌按蚊酯酶 ( EST)酶谱 ,EST出现两组区带 ,微小按蚊 (含 2个不同地株 )存在遗传上的多态现象 ,乌头按蚊 EST酯酶相对简单。各自均有稳定的酶带 ,并可根据 Rm值结合各自特殊酶带区分成 3个不同的种     

Organization of sensory and motor nuclei of the trigeminal nerve in lampreys

Anterograde and retrograde HRP transport were used to elucidate the primary central projections of the trigeminal nerve in a lamprey, Lampetra japonica, by application to the ophthalmic, apical, basilar, suborbital, and mandibular branches of the trigeminal nerve. (1) Most of the trigeminal and a few facial ganglion cells were labeled. The ganglion cells of each nerve were distributed in separate areas within their respective ganglia. (2) Some ipsilateral medullary and spinal dorsal cells were labeled after HRP application to the ophthalmic and apical nerves, but there was no contralateral labeling. (3) Most of the neurons of the trigeminal motor nucleus were labeled, and when the apical or the basilar nerve was labeled, in each case a cluster of small motor neurons was found ventrolateral to the classic motor nucleus. (4) Miscellaneous neurons were found scattered along the course of the descending trigeminal tract and nucleus in all cases except after application to the mandibular branch. The shape, size, and distribution patterns of these neurons were varied, and several characteristics indicated that they were sensory in nature. (5) In the rostral part of the medulla, sensory fibers of each nerve showed restricted localization within the descending trigeminal tract and nucleus. When compared to the distribution of the same fibers in the hagfish Eptatretus burgeri, another member of the cyclostomes, the distribution pattern in the lampreys studied was closer to the type seen in gnathostomes.     

DDT indoor residual spray, still an effective tool to control Anopheles fluviatilis-transmitted Plasmodium falciparum malaria in India

This study from two districts of Orissa State which are endemic for Plasmodium falciparum transmitted by Anopheles fluviatilis and A. culicifacies investigated the impact of dichlorodiphenyl trichloroethane (DDT) indoor residual spraying, in view of the ongoing discussion on phasing out DDT in India. Based on their high annual parasite incidence and logistical considerations, 26 villages in Malkangiri and 28 in Koraput district were selected for DDT spraying. For comparison, six and four unsprayed villages were chosen from the same districts. In each district, the prevalence of malaria infection and incidence of malaria fever, indoor resting density and parous rate of the vectors, and their susceptibility to DDT were monitored in six and three villages selected randomly from the sprayed and unsprayed groups respectively. Anopheles fluviatilis was susceptible to DDT while A. culicifacies was resistant. DDT residual spraying with 1 g/m(2), was carried out in October-November 2001. Spraying 74-86% of human dwellings and 100% of cattle sheds brought down the indoor resting density of A. fluviatilis by 93-95%. This was associated with a significant reduction of incidence of malaria fever as well as prevalence of malaria infection from November to February in both districts. The spraying also seemed to impact on vector longevity, and a residual effect of DDT on the sprayed walls was observed up to 10-12 weeks despite re-plastering. Hence DDT spraying can still be an effective tool for controlling fluviatilis-transmitted malaria. Although this species is exophilic, its nocturnal resting behaviour facilitates its contact with the sprayed surfaces. DDT is still useful for residual spraying in India, particularly in areas where the vectors are endophilic and not resistant.     

微小按蚊和溪流按蚊翅斑形态的比较

目的：比较微小按蚊和溪流按蚊翅斑的形态，了解它们的变异情况，寻找可靠的鉴别特征。方法：微小按蚊采自云南省景洪县基诺乡，溪流按蚊采自广西壮族自治区凌云县。将母蚊产的卵，在实验室饲养至成蚊，再将成蚊的翅制成玻片标本，在显微镜下测量标本的翅长和部分翅斑的长度。结果：共检查微小按蚊雌蚊翅５２个，雄蚊翅６０个，溪流按蚊雌蚊翅４０个，雄蚊翅６０个。认为翅前缘脉上分脉前白斑（ＰＳＰ）的有无和分脉白斑与分脉暗斑比例（ＳＰ／ＳＤｒａｔｉｏ）的大小，是鉴别微小按蚊和溪流按蚊的重要依据。结论：无论是雌蚊还是雄蚊，微小按蚊的翅斑形态与溪流按蚊的翅斑形态均有较为明显的差异。     

Radioautographic evidence for both orthograde and retrograde axonal transport of labeled compounds after intraocular injection of [H]proline in the lamprey (Lampetra fluviatilis)

[³H] Proline injected intraocularly in lampreys has been shown to be bidirectionally transported: 24–96 h after the injection, retinofugal fibers and terminals as well as nerve cell bodies at the origin of the retinopetal system were intensely labeled. These results are at variance with the generally held belief that [³H]proline is taken up only by cell bodies and transported by the anterograde flow. The significance of the retrograde axonal transport of [³H]proline in the lamprey retinopetal system is discussed.     

Multigeneration assessment of nonylphenol and endosulfan using a model Australian freshwater fish, Melanotaenia fluviatilis

Changes over two generations in offspring and reproductive ability were recorded in crimson-spotted rainbowfish (Melanotaenia fluviatilis), a model Australasian freshwater fish, following a 24 h exposure to nominal nonylphenol concentrations of 50, 100, 500, 1000, 2250, and 5000 microg/L and following a 4 h exposure to nominal endosulfan concentrations of 1.0, 5.0, 10, 22, 33, and 50 microg/L. There were also four replicated control treatments: control 1 and 2 and solvent control 1 and 2, as well as "positive" female and male controls: 1 microg/L estradiol 1 and 2 and 1 microg/L testosterone 1 and 2. Results suggested that there may be some parental transfer of toxicants to embryos even over this short exposure period. Fertility of M. fluviatilis was reduced by a 24 h pulse exposure of adults to 100 microg/L nonylphenol and a 4 h exposure to 1.0 microg/L endosulfan. Hatch rates were significantly reduced after exposure to nonylphenol, endosulfan, and estradiol control but not in solvent controls and testosterone control. Significant correlations were found between reproductive and physiological parameters for nonylphenol and endosulfan exposed F0 adult rainbowfish. The major reproductive effects were on hatchability of the F1 generation and the gonadosomatic indices of male F1. The respective nominal NOEC and LOEC's for nonylphenol were 50 and 100 microg/L, and for endosulfan were <1.0 and 1 microg/L. These observed effects have the potential to significantly impact exposed rainbowfish populations through the observed approximately 45% reduction of hatchability and thus larval production.     

Suppression of neuronal excitability by the secretion of the lamprey (Lampetra japonica) provides a mechanism for its evolutionary stability

Lampreys are one of the most primitive vertebrates still living today. They attach themselves to the body surface of the host fish through their sucker-like mouths and suck blood of the host for days. Recent fossil evidence has indicated that morphology of lampreys in the late Devonian period, over 360 million years ago, already possessed the present day major characteristics, suggesting the evolutionary stability of a highly specialized parasitic feeding habit. Obviously, nociceptive responses and hemostasis of the host are two major barriers to long-term feeding of the parasitic lamprey. It has been found, to counteract hemostasis of the host, that paired buccal glands of lampreys secrete antihemostatic compounds to prevent blood of the host from coagulation. However, it is not known how lampreys make the host lose nociceptive responses. Here, we prepared components of the crude extract from the buccal glands of the lampreys (Lampetra japonica). Then, we show that crude extract and one of its purified components reduce the firing frequency of neuronal action potentials probably through inhibiting the voltage-dependent Na⁺ channels. As the voltage-gated Na⁺ channels are highly conserved throughout evolution, we argue that the secretion of the lampreys could exert the similar effect on the Na⁺ channels of their host fish as well. Therefore, together with its antihemostatic effect, the secretion due to its inhibitory effect on neuronal excitability might provide a mechanism for the parasitic lampreys to keep their evolutionary stability. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Shaopeng Chi, Rong Xiao, and Qingwei Li contributed equally to this work.