Nitroxidergic Cells in the Intestine of the Bivalve Mollusk Modiolus kurilensis

The distribution of nitroxidergic (NO-ergic) cells in the direct and recurrent loops of the midgut and in the hindgut of the bivalve mollusk Modiolus kurilensis was studied using a NADPH-diaphorase (NADPH-d) histochemistry [13]. Intraepithelial NO-ergic cells were found in the intestinal groove, in the major typhlosole of the direct loop, in the recurrent loop of the midgut, as well as in the hindgut. The apical processes of these cells are directed to the intestinal lumen, whereas the basal processes connect to the basiepithelial NO-ergic plexus. The latter, in turn, have separate fibers that are in contactswith the subepithelial NO-ergic plexus. Both plexuses are well developed in the intestinal groove of the direct loop and in the recurrent loop of the midgut, as well as in the hindgut. In the major typhlosole and crystalline style sac of the direct loop, both basi- and subepithelial NO-ergic plexuses are less developed. In the minor typhlosole, the basiepithelial NO-ergic plexus is absent and only single fibers of the subepithelial plexus occur. In the connective tissue and muscular layers of the recurrent loop of the midgut, subepithelial NO-ergic nerve cells were found.     

Distribution of vasoactive intestinal peptide-like immunoreactivity in the taste organs of teleost fish and frog

Summary Using immunohistochemistry, vasoactive intestinal peptide (VIP) was visualized in taste bud cells of the carp, Cyprinus carpio, and the European catfish, Silurus glanis, by means of light and electron microscopy. Intracellular membrane systems, presumably smooth endoplasmic reticulum, of light (sensory) cells, but not of dark (supporting) cells and basal cells, were densely labelled with antibody. In the frog (four species: Rana temporaria, R. ridibunda, R. arvalis, R. pipiens), taste bud cells did not label. However, the dense basal nerve fibre plexus, some subepithelial ganglionic cells, but no ascending intragemmal fibres, were immunoreactive. In fish, the results support evidence that VIP is involved in the modulation of taste transduction at the level of receptor cells. In the frog, an indirect, possibly vasodilatatory effect on taste perception may be considered.     

The organization of the nervous system in Plathelminthes. The neuropeptide F-immunoreactive pattern in Catenulida,Macrostomida, Proseriata

The organization of the nervous system of Archilopsis unipunctata Promonotus schultzei and Paramonotus hamatus (Monocelididae, Proseriata) and Stenostomum leucops (Catenulida) and Microstomum lineare (Macrostomida) was studied by immunocytochemistry, using antibodies to the authentic flatworm neuropeptide F (NPF) (Moniezia expansa). The organization of the nervous system of the Monocelididae was compared to that of the nervous system of Bothriomolus balticus (Otoplanidae), a previously studied species of another family of the Proseriata. The results show that the main nerve cords (MCs), independent of lateral or ventral position in the Monocelididae and the Otoplanidae, correspond to each other. The study also confirms the status of the lateral cords as main cords (MCs) in S. leucops and M. lineare. Common for MCs in the members of the investigated taxa are the following features: MCs consist of many fibres, originate from the brain and are adjoined to 5-HT-positive neurons. In Monocelididae and Otoplanidae, the MCs additionally have the same type of contact to the pharyngeal nervous system. Also common for both proseriate families is the organization of the two lateral nerve cords, with weaker connections to the brain, and the pair of dorsal cords running above the brain. The organization of the minor cords differs. The Monocelididae have a pair of thin ventral cords forming a mirror image of the dorsal pair. Furthermore, an unpaired ventral medial cord connecting medial commissural cells was observed in P. schultzei. Marginal nerve cords, observed in Otoplanidae, are absent in Monocelididae. All minor nerve cords are closely connected to the peripheral nerve plexus. The postulated trends of condensation of plexal fibres to cords and/or the flexibility of the peripheral nerve plexus are discussed. In addition, the immunoreactivity (IR) pattern of NPF was compared to the IR patterns of the neuropeptide RFamide and the indoleamine, 5-HT (serotonin). Significant differences between the distribution of IR to NPF and to 5-HT occur. 5-HT-IR dominates in the submuscular and subepidermal plexuses. In the stomatogastric plexus of M. lineare, only peptidergic IR is observed in the intestinal nerve net. The distribution of NPF-IR in fibres and cells of the intestinal wall in M. lineare indicates a regulatory function for this peptide in the gut, while a relationship with ciliary and muscular locomotion is suggested for the 5-HT-IR occurring in the subepidermal and submuscular nerve, plexuses. In M. lineare, the study revealed an NPF- and RFamide-positive cell pair, marking the finished development of new zooids. This finding indicates that constancy of these cells is maintained in this asexually reproducing and regenerating species.     

中华稻蝗消化道内分泌细胞的鉴别与定位

采用整块组织Grimelius银染法和过氧化物酶标记的链霉亲和素免疫组织化学技术,结合生物统计学分析,对中华稻蝗Oxya chinensis消化道内分泌细胞进行鉴别与定位。结果表明：嗜银细胞分布于中华稻蝗的胃盲囊、中肠和后肠各段,以中肠和直肠中最多（P<0.05）, 前肠中未见分布。免疫组织化学法检测出了五羟色胺（5-hydroxytryptamine, 5-HT）、 胃泌素（gastrin, Gas）、 胰高血糖素（glucagon, Glu）和胰多肽（pancreatic polypeptide, PP）细胞, 未检出生长抑素（somatostatin, SS）细胞。免疫阳性细胞分布于中肠和后肠中, 前肠中未见分布。5-HT细胞和Gas细胞均主要分布于胃盲囊、中肠及直肠中,且均以直肠中最多（P<0.05）。Glu细胞在胃盲囊及整个中、后肠均有分布, 在中肠和直肠中最多（P<0.05）。PP细胞主要分布于中肠、回肠和直肠中,中肠中分布密度最大（P<0.05）。本研究显示中华稻蝗消化道中存在多种内分泌细胞,它们的分布情况与其他节肢动物相比存在一定的共性,也有其一定的特异性,可能与中华稻蝗特定的消化道结构和消化生理功能有关。     

How much can Conus swallow? observations on molluscivorous species

Feeding of three species of molluscivorous Conus, C. textile,C. bandanus and C. omaria, was studied in aquaria. Conus spp.are able to kill and remove from the shell prey larger thanthemselves. Also, Conus swallowed prey with weight up to halfthat of the predator. Estimates suggest that molluscivorousspecies of Conus are probably able to swallow prey with a shellvolume reaching 85% of that of the predator, depending on theshape of the prey's body. It is confirmed that the thinningof the inner shell walls in Conus is connected with the abilityto swallow voluminous prey. Digestion of prey occurs in boththe oesophagus and stomach. (Received 9 August 2006; accepted 4 January 2007)     

Effect of copper ions on spatial density of NO synthase-positive cells in intestine of the mussel <Emphasis Type="Italic">Crenomytilus grayanus</Emphasis> (mollusca: bivalvia: mytilidae). A histochemical study

By the histochemical method of detection of NADPH-diaphorase (NADPH-d) (EC1.6.99.1) [1] the state of nitroxidergic enteric nervous system of the mussel Crenomytilus grayanus was studied under conditions of an increased copper concentration in water. Under the action of copper ions the density of distribution of NADPH-d-positive cells has been established to be changed as compared with control throughout 28 days. A sharp rise of proportion of the labeled cells and their enzyme activity was noted after one day of the experiment. The labeled bipolar cells were of dark blue color and were located within the epithelium. There were revealed numerous nerve fibers penetrating the intestinal epithelium throughout its entire length as well as bipolar nerve cells in epithelium of the minor typhlosole and of crystalline style sac; in control molluscs the NADPH-d-positive cells in these parts were absent. After 7 days the difference between control and experimental decreased and remained at this level after 14 days, while after 21 days of exposition the proportion of labeled cells in the experimental mussels was lower than in control, but increased again after 28 days. It is suggested that nitric oxide is an important protective factor of the intestinal epithelium of the mussel C. grayanus and participates in adaptation of this mollusc to action of the elevated concentration of copper ions in water.     

Ultrastructure of sea urchin tube feet

Summary An analysis of the ultrastructure of the tube feet of three species of sea urchins (Strongylocentrotus franciscanus, Arbacia lixula and Echinus esculentus) revealed that the smooth muscle, although known to be cholinoceptive, receives no motor innervation.The muscle fibers are attached to a double layer of circular and longitudinal connective tissue which surrounds the muscle layer and contains numerous bundles of collagen fibers. On its outside, the connective tissue cylinder is invested by a basal lamina of the outer epithelium to which numerous nerve terminals are attached. These are part of a nerve plexus which surrounds the connective tissue cylinder. The plexus itself is an extension of a longitudinal nerve that extends the whole length of the tube foot. It is composed of axons, but nerve cell bodies and synapses are conspicuously lacking, suggesting that the axons and terminals derive from cells of the radial nerve. Processes of the epithelial cells penetrate the nerve plexus and attach to the basal lamina. There is no evidence that the epithelial cells function as sensory cells.On the basis of supporting evidence it is suggested that the transmitter released by the nerve terminals diffuses to the muscle cells over a distance of several microns and in doing so affects the mechanical properties of the connective tissue.Supported by the Sonderforschungsbereich 138 of the Deutsche Forschungsgemeinschaft     

Distribution of substance p-like immunoreactivity in nerves of the gastrointestinal tract of the frog Rana esculenta L.

Summary Substance P-like immunoreactivity in the alimentary canal of the frogRana esculenta L. was studied by means of the indirect immunoperoxidase method. In all segments of the gastrointestinal tract, immunoreactivity was revealed in both the myenteric and the submucosa plexus. Stained nerve cells were observed in the myenteric plexus but not in the submucous plexus. The proximal part of the oesophagus and hindgut were free of immunoreactive perkarya. The stained nerve cells were of the Dogiel type I category in the foregut, and type II in the midgut. Both the musculature and gastrointestinal glands were supplied with immune-positive fibres. These results indicate that substance P may play similar roles in the frog gut, as described previously in mammals and fish.     

Types of Androecium in the Fabaceae of SW Europe

We studied the morphology of the androecium in 168 species andsubspecies of Fabaceae from SW Europe and its relationship withnectar production. Six androecium types were recognized: monadelphous;pseudomonadelphous without basal fenestration; pseudomonadelphouswith basal fenestration; diadelphous; reduced diadelphous; andandroecium with free stamens. The monadelphous androecium appearsin the tribe Genisteae, inOnonis, and inGalega officinalis,andthe pseudomonadelphous without basal fenestration only in thegenusCoronilla,with both types having the same functionality—theyare linked to the absence of nectar from an intrastaminal nectary,their taxa being mostly polliniferous. The pseudomonadelphousandroecium with basal fenestration appears in around 38% ofthe taxa studied and has the same functionality as the diadelphousandroecium: there is nectar secretion from an intrastaminalnectary in both. The reduced diadelphous androecium only appearsin three species (Biserrula pelecinus, Vicia pubescensandAstragalusepiglottis), and its functionality could be related to the syndromeaccompanying autogamy in Angiosperms. The free stamen androeciummay imply a greater nectar production than other types.Copyright1999 Annals of Botany Company. Fabaceae, Leguminosae, androecium, nectar, floral biology.     

棉铃虫幼虫感染棉铃虫微孢子虫后的组织病理变化

1997年田间调查时发现一种寄生于棉铃虫Helicoverpa armigera（Hübner）的微孢子虫Nosema sp.,它对棉铃虫有较强的致病力并可经卵垂直传播。利用透射电镜对棉铃虫幼虫感染该微孢子虫后的组织病理变化进行了初步观察。结果表明：该微孢子虫可侵染棉铃虫的中肠、马氏管、脂肪体、神经等组织;侵染后可导致寄主中肠的微绒毛脱落,线粒体内脊排列方向发生变化,线粒体整体发生变形并最终瓦解;内质网发生断裂;细胞核体积变小并变形,但该微孢子虫并不入侵细胞核;马氏管膨大,边缘向外突出隆起;神经细胞的细胞核变成长条形,细胞界线模糊;在神经细胞内也发现了微孢子虫孢子,证明该微孢子虫也入侵寄主神经细胞。     

Neuropeptides in the intestine of two teleost species (Oreochromis mossambicus,Carassius auratus): Localization and electrophysiological effects on the epithelium

Summary The presence of bioactive peptides in the gut and their possible electrophysiological effects on the intestinal epithelium were studied in two teleost species, the tilapia (Oreochromis mossambicus) and the goldfish (Carassius auratus). Vasoactive intestinal polypeptide-like immunoreactive nerve fibres were found beneath the intestinal epithelium of both species. Galanin-, metenkephalin-and calcitonin gene-related peptide-like immunoreactive nerve fibres were found exclusively in the mucosa of the tilapia. Both species had vasoactive intestinal polypeptide-, enkephalin- or neuropeptide Y-like immunoreactive endocrine cells; calcitonin gene-related peptide-like immunoreactive endocrine cells were additionally found in the tilapia. Somatostatin- and dopamine--hydroxylase-like immunoreactivities were not observed. Nerve cell bodies in the myenteric plexus of both species showed immunoreactivity for calcitonin gene-related peptide-, vasoactive intestinal polypeptide-, and galanin-like peptide. Enkephalin-like immunoreactive nerve cell bodies were present in the tilapia only. None of the peptides had a pronounced electrogenic effect. However, calcitonin gene-related peptide added to stripped intestinal epithelium of the tilapia, reduced the ion selectivity, and addition of galanin increased the ion selectivity. In goldfish intestine, both galanin and calcitonin gene-related peptide were without effect. Enkephalin counteracted the serotonin-induced reduction of the ion selectivity of the goldfish intestinal epithelium, but had no effect on the tilapia epithelium. In both species, vasoactive intestinal polypeptide reduced the ion selectivity of the intestinal epithelium, and neuropeptide Y induced an increase of the ion selectivity. Somatostatin showed no effect on the epithelial ion selectivity of either species. Tetrodotoxin did not inhibit the effects of the peptides studied. The changes in ion selectivity suggest that the enterocytes may be under the regulatory control of these peptides.     

Salt Glands in Pappophorum (Poaceae)

Salt glands were observed in two species of Pappophorum, belongingto the tribe Pappophoreae (Chloridoideae, Poaceae). Glands resemblethose described in other genera of the Gramineae; they comprisetwo cells, a large basal one and smaller upper one. Gland densityper unit surface was much higher in P. philippianum, a facultativehalophyte, than in P. pappiferum, a glycophyte. The relevanceof the recretion process for the elimination of accumulatedNa in these two species is considered. The evolutionary significanceof the presence of glands in Pappophoreae and other membersof the Chloridoideae is discussed. Salt glands, Pappophorum philippianum, P. pappiferum, Poaceae     

NADPH-diaphorase localization in the radial nerve cords of the starfish Patiria pectinifera

The presence and localization of NADPH-diaphorase (NADPH-d) in the radial nerve cords of Patiria pectonifera was shown by electron histochemistry. NADPH-d-positive structures were found in ectoneural and hyponeural regions of the radial nerve cord. Ultrastructural localization of NADPH-d was detected in neurons, sensory cells, supporting cells, and in the nerve plexus. The highest enzymatic activity in ectoneural region of the radial nerve cord is due, presumably, to the involvement of NADPH in sensory signal processing.     

NERVOUS ORGANIZATION AND THE PROBLEM OF THE SYNAPSE IN ACTINIA EQUINA

The nervous system of Actinia equina was studied by routinehistological methods and by metallic impregnation techniques.Some preliminary results from electron microscopy are included. The organization of the nervous system of this species is morecomplex than that of other anthozoans; it consists of two interconnectednerve plexuses which are developed to differing degrees in variousparts of the body. These are: (1) a superficial (outer) plexuslying in the ectoderm, and (2) a deeper (inner) plexus constitutingthe main nerve net, lying in the mesoderm. The former is composedof bipolar and multipolar nerve cells, and the latter of multipolarcells. Receptor cells in the ectoderm make contact with fibersof the ectodermal plexus. Processes from the mesodermal plexusrun out to the muscle fibers. Connections between the receptor cells and the nerve processesof the superficial plexus and between the processes of the cteeperplexus and the muscle fibers appear to be of the discontinuous(synaptic) type. In the nerve nets themselves, although someconnections resembling synapses have been seen, most of thenerve elements stand in direct connection with one another,so that the system must be regarded as at least partly syncytial.Evidence is given for the growth of the nerve net, in step withthe general growth of the animal, by division of nuclei followedby their movement apart within the syncytium. The distribution of the nerve elements in various parts of thebody, the interconnections between these regions, and the cytologicalcharacteristics of the cells are described. Ways in which excitationcould pass from one part to another are discussed.     

Some morphological and histochemical features of the midgut myenteric plexus of the common European frog, Rana esculenta.

The neuron morphology and distribution of four putative transmitters were investigated in the myenteric plexus of frog (Rana esculenta) midgut. The gross morphology was revealed by NADH-diaphorase histochemistry, and the shape of the neurons by silver impregnation. Nerve cells had heterogeneous distribution: they either formed ganglia or placed as solitary neurons in the duodenum, while in the rest of the midgut only solitary neurons were observed. Three morphologically distinct cell types were revealed by silver impregnation: mainly type I and type II neurons cells were seen in the duodenum, while the rest of the intestine contained type II and III cells. Catecholamine fluorescence was revealed in nerve fibres in the duodenum, while few small nerve cells were observed in the small intestinal region. Acetylcholinesterase histochemistry showed strongly reactive nerve cells that were associated with the main fibre bundles in the duodenum. Only longitudinally oriented fibres and occasionally stained neurons were seen in the small intestine. Substance P immunocytochemistry revealed an extensive plexus, which contained a moderate number of stained perikarya in the full length of the midgut. Gamma-aminobutyric acid showed non-uniform distribution in the two parts of the midgut: a stronger and more regular fibre staining was found in the duodenum then in the rest of the intestine. Ultrastructural observations demonstrated that intrinsic neurons received synaptic inputs from the profiles contained agranular vesicles, while "P"-type profiles established close contacts with neurons. Both profile types formed close contacts with the smooth muscle cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Toxoglossan gastropods of the subfamily Crassispirinae (Turridae) lacking a radula, and a discussion of the status of the subfamily Zemaciinae

Two new species of Horaiclavus, lacking radula, venom glandand proboscis, are described. The genus is placed in the subfamilyCrassispirinae (Turridae). Both species possess a peculiar foregutstructure, the muscular rhynchodaeal outgrowth situated in therhynchocoel. The possible function of the rhynchodaeal outgrowthis discussed. Other studied species of Horaiclavus possess aradula of a typical ‘crassispirine’ type but lackthe outgrowth. The anatomy of the foregut of the new speciesis superficially similar to that of Zemacies excelsa (Turridae:Zemaciinae), which also possesses an additional structure ofthe rhynchocoel, namely the ‘pyriform gland’. Conchologically,there is no resemblance between Zemacies and Horaiclavus andit is concluded that similar foregut arrangement appeared independentlyin both lineages. A new monotypic subfamily Zemaciinae was erectedmostly on the basis of the unique foregut arrangement of Zemaciesexcelsa. We express doubts concerning the importance of thesecharacters in establishing a new taxon of subfamilial rank andtherefore the validity of the subfamily Zemaciinae. (Received 16 May 2007; accepted 1 October 2007)     

Microsatellite cross-species amplification in the genus Littorina and detection of null alleles in Littorina saxatilis

Microsatellite DNA is widely used as population genetic marker,but the cost of using microsatellites is high, as they usuallyneed to be developed and optimized for each species separately.Cross-species amplification of microsatellites is thereforecommonly applied to bring down the cost, but it can also involvegenotyping errors. We studied cross-species amplification ofmicrosatellites in four species of the Atlantic group of Littorina(Neritrema): L. saxatilis (Olivi, 1792), L. obtusata (Linnaeus,1758), L. fabalis (Turton, 1825) and L. arcana Hannaford Ellis,1978 to investigate whether markers originally developed fora more distantly related Pacific species [L. subrotundata (Carpenter,1864)] suffered from more amplification problems than markersdeveloped for one of the species in the Atlantic group (L. saxatilis).We also compared variation in amplification success among thespecies and among different regions in the NE Atlantic. Approximatelyhalf of the 12 primers developed for L. subrotundata and theseven primers developed for L. saxatilis were successfully amplifiedin other species of the subgenus. The success was dependenton phylogenetic distance among species within the subgenus.On the other hand, the variation in performance of the locibetween geographically remote populations of the same specieswas as high as variation among the species. In earlier studiesstatistical analyses indicated that several loci showed a heterozygotedeficiency due to null alleles. The presence of null alleleswas confirmed by a segregation analysis of the microsatelliteloci in eight half-sib families of L. saxatilis. (Received 2 April 2007; accepted 19 November 2007)     

取食转Bt基因水稻对稻纵卷叶螟幼虫中肠的组织病理学效应

利用透射电镜观察了稻纵卷叶螟 Cnaphalocrocis medinalis（Guenée）幼虫取食转Bt基因水稻后中肠的组织病理变化。结果表明：稻纵卷叶螟幼虫取食转cry1Ab基因水稻后,中肠上皮细胞的线粒体先发生形态变化,随连续取食时间的延长线粒体出现凝聚、内嵴稀疏、空泡化等,在后期还呈凝聚态随突起脱落或沿杯腔边沿单一排列。内质网的变化也很明显,病变过程中伴随着粗糙内质网的肿胀、核糖体脱落,粗糙内质网增多等现象。细胞核的变化较小,在处理后期出现细胞核拉长、核仁聚集等变化。组织病变程度不一,有的细胞在病变早期就出现了空泡化。     

Midgut pseudotumors and the maintenance of tissue homeostasis: Studies on aging and manipulated stick insects

Stick insects (Carausius morosus) develop pseudotumors in aging adults. Pseudotumor formation starts at the M2 midgut region where an accumulation of stomatogastric nerve terminals is observed. Pseudotumors arise from dying columnar cells whose basal parts form an “amorphous substance” at the basement membrane whereas the apical parts, including the nucleus, are expelled into the gut lumen. The “amorphous substance” is ensheathed by hemocytes. These nodules, which do not melanize, characterize the phenotype of the pseudotumors. With age, cell death and pseudotumor infestation increases. It is shown that the maintenance of midgut tissue homoeostasis is disturbed and becomes more serious with growing pseudotumor incidence. The increased death rate of differentiated columnar cells is no longer compensated by the proliferation of regenerative cells, i.e., intestinal stem cells, in the midgut nidi. The appearance of “holes” in the intestinal wall is evidently a causative factor of premature death. Extirpation of the hypocerebral ganglion in young adults of the stick insect (before the onset of spontaneous pseudotumor formation) provokes the apoptosis of a large number of columnar cells within 24 h and the formation of pseudotumors that are histologically identical with spontaneous ones. We conclude that the stomatogastric nervous system plays a decisive role in the regulatory mechanism maintaining midgut tissue homeostasis. The possibility of experimentally manipulating the regulatory system provides a valuable tool for the exploration of extrinsic factors involved into the feedback circuitry of tissue homeostasis. The fact that comparable pseudotumors were observed in a number of orthopteromorphan species, where they could also be induced by the interruption of the stomatogastric nervous system, indicates that its role in tissue homoeostasis may be widespread in insects and possibly represent a general principle. J. Morphol., 2009. © 2008 Wiley‐Liss, Inc.