Hormonal control of egg-laying in the marine pulmonate,Onchidium verruculatum

Extirpation of the pleurovisceral ganglia (PV) blocked egg-laying whereas reimplantation of PV or injection of a PV homogenate into PV-less animals restored the egg-laying capacity of the marine pulomonate, O. verruculatum. Injection of PV homogenate induced egg-laying in intact, mature individuals within 15–45 minutes. Boiling of the homogenate for 15 minutes did not abolish its egg-laying efficacy. However, after incubation with trypsin, a PV homogenate lost its potency. Homogenates of PV from colchicinized animals could not induce egg-laying in intact Onchidium. Similarly, colchicinized animals did not respond to a PV ectract from intact Onchidium. It is hypothesized that egg-laying in O. verruculatum is under the control of a heat-stable, trypsin sensitive hormone secreted by the PV ganglia.     

Preliminary evidence for the hormonal control of urea concentration in the marine pulmonate,Onchidium verruculatum

Changes in blood, hepatopancreas and kidney urea concentrations in O. verruculatum have been assessed in response to endocrinological provocations. Two hr after pleurovisceral (PV) ganglion removal blood and nephridial urea levels were found to be significantly lowered and elevated respectively, whereas the hepatopancreas urea value remained unaltered, over the sham control. Unboiled and boiled macerates of PV (2 gn/animal) ganglion were effective in significantly inhibiting urea levels in blood and kidney of normal intact individuals. The possibility of a neurohormone from the PV, influencing tissue urea levels is discussed.     

Regulation of ammonia (NH3-N) metabolism in the marine pulmonate,onchidium verruculatum. I. effects of a neuroendocrine centre on tissue ammonia levels

Effect of ganglionic extirpations and replacement on the ammonia levels in the blood and various tissues of the marine pulmonate, O. verruculatum was studied. Three hrs after extirpation of the pleurovisceral (PV) complex only and not any other ganglia, revealed a significant (P < 0.001) decline in the blood and foot ammonia levels and significant (P < 0.001) increment in the hepatopancreatic ammonia level. However, no change was observed in the mantle and nephridial ammonia levels. Replacement of the PV complex, either via implantation of intact ganglia or boiled and unboiled homogenate administration (1 gn/animal) into the ganglionectomised group, restored ammonia levels in the blood and foot and showed significant (P < 0.005) decrease in hepatopancreatic ammonia levels. The results are discussed in the light of hormonal regulation of the nitrogen metabolism.     

Hormonal control of blood chloride in the marine pulmonate,onchidium verruculatum

A search for endocrinological factors inO. verruculatum revealed that three hours after right pleural ganglion extirpation blood chloride is significantly (P<0.01) sinked. Administration of right pleural ganglion homogenate (I gang/animal) into depleuralised snails significantly (P<0.001) enhances the blood chloride level after three hrs. Removal of the ganglia other than the right pleural provokes a significant (P<0.01) decline in blood chloride profile in these animals. However, replacement therapy either via homogenate injection or reimplantation of the particular ganglion into extrapleural ganglionectomised animals is ineffective in restoring the chloride levels. It is argued that only right pleural ganglia control blood chloride via vascular channels.     

Trail‐following and trail‐searching behaviour in homing of the intertidal gastropod mollusc,Onchidium verruculatum

When uncovered by the tide, Onchidium verruculatum leaves its place of hiding, grazes on the rock surface, and thèn returns to its own home. Onchidium will follow its own mucus trail, most frequently towards the origin. This behaviour explains homing when the outward path is partly or completely retraced. Sometimes, however, homing occurs without contact with the outward trail. It was observed that trails were followed more closely at low humidities than at high humidities. No evidence was found for any method of orientation other than detection of chemical trials: when displaced onto sand Onchidium tend simply to crawl in a spiral until they contact their own trail. In addition to being a safe retreat, the home provides a fixed starting point to feeding excursions : this may facilitate re‐location of preferred feeding areas.     

Three new species of <Emphasis Type="Italic">Disterigma</Emphasis> (Ericaceae: Vaccinieae) from Western Colombia,with comments on morphological terminology

Three new endemic species are described and illustrated from the floristically diverse western mountain ranges of Colombia. Disterigma appendiculatum, D. hiatum, and D. verruculatum have interesting floral characters that are unique in the genus and in the Vaccinieae. These new morphological characters and the terminology adopted for bracteoles and staminal appendages are briefly discussed.     

Fine structure of the dioptric apparatus in the stalk eye of Onchidium verruculatum (Gastropoda, Stylommatophora): a distinct lamellar substructure of the lens

 The dioptric apparatus of the stalk eye in Onchidium verruculatum, including a tentacular epidermis, a cornea, and a lens, was examined using transmission electron microscopy. The tentacular epidermis was formed by columnar epidermal cells, sensory dendrites, and glandular cells. The cornea was an anterior part of the eye vesicle and consisted of corneal cells which contained abundant glycogen particles but no dark pigment granules in their cytoplasm. An acellular, transparent, ellipsoidal lens was located in the center of the eye vesicle. The lens showed a marginal zone, an outer zone, a transitional zone, an inner zone, and a central region arranged concentrically. The outer zone was the most intense electron-dense region and was finely granular in structure. The marginal zone was also finely granular and surrounded the outer zone with many hair-like slender strands on the retinal side. Toward the center of the lens this homogeneous fine granularity gradually changed into globular or rod-like substructures, about 30 nm in diameter, and then abruptly transformed into a lamellar substructure of about 30 nm in thickness. The inner zone contained a mosaic of lamellar substructures which were arranged in a fingerprint pattern that was particularly enhanced with periodic acid methenamine silver proteinate staining. The center itself consisted of deformed lamellar substructures. The concentric arrangement of substructures inside the lens of the O. ver-ruculatum stalk eye is probably responsible for the concentration and/or refraction of light. Accepted: 5 December 1997     

Role of microstructure of nerve impulse train in relation to transmission of neuronal activity and coding mechanism of neural information

Input-output relation were of giant neurons of a marine mollusc, Onchidium verruculatum, and a computer-simulated neuron investigated in terms of microstructure of nerve impulse train. The microstructure of input impulse train, the size of a unitary EPSP, and the extent of spontaneous firing activity of a single neuron had an important influence upon the effective summation of arriving synaptic inputs, the elicitation of output spikes, and intervals between succeeding output spikes. The neuron responded differently to respective input trains with different time structures, i.e. it discriminated input time pattern to various degrees. The manner in discrimination of input time pattern was dependent on the size of the unitary EPSP and the extent of the spontaneous firing activity, if it had. Some discussions were made with regard to possible coding systems of neural signal, assuming a frequency code and/or a pattern code.     

Reduction of a model for an Onchidium pacemaker neuron

The eight-variable model for the giant neuron localized in the esophageal ganglia of the marine pulmonate mollusk Onchidium verruculatum is reduced to four-and-three-dimensional systems by regrouping variables with similar time scales. These reduced models replicate the complex behavior including beating, periodic bursting and aperiodic bursting displayed by the original full model when the parameter I _ext representing the intensity of the constant DC current stimulation is varied across a wide range. The complex behavior of the full model arises from the interaction of fast and slow dynamics, and depends on the time scale C _s of the slow dynamics. The four-variable reduced model is constructed independently from the parameter C _s so that it reproduces the two-dimensional bifurcation structure of the full model for the two parameters I _ext and C _s . The three-variable reduced model is derived for a specific value of C _s . The parameters of this model are tuned so that its one-parameter bifurcation diagram for I _ext closely matches that of the full model. Correspondence between bifurcation structures ensures that both reduced models reproduce the various discharge patterns of the full model. Similarity between the full and reduced models is also confirmed by comparing mean firing frequencies and membrane potential waveforms in various regimes. The reduction exposes the factors essential for reproducing the dynamics of the full model; indeed, it shows that the eight variables representing the membrane potential and seven gating variables of six ionic currents in the full model account, in fact, for three basic processes responsible for excitability, post-discharge refractoriness and slow membrane modulation. Received: 7 May 1996 / Accepted 4 December 1997     

Notes on the genus Orobanche in Italy: 3. Taxa described by A. Bertoloni

Abstract

Original material of the 12 taxa described as new by Bertoloni has been examined, and typification of their names is discussed. Lectotypes are designated for 11 of Bertoloni's names, one (O. densiflora Bertol.) had been lectotypified before. Orobanche bicolor Bertol. (non C. A. Mey.) belongs to O. cernua L., O. cruenta Bertol. to O. gracilis Sm., O. stricta Moris ex Bertol. to O. schultzii Mutel, O. thyrsoidea Moris ex Bertol to O. rigens Loisel., O. crithmi Bertol. to O. minor Sm., O. vitalbae Bertol. to O. artemisiae-campestris Gaudin, O. fragrantissima Bertol. to O. lutea Baumg., O. laurina Bertol. to O. hederae Duby, O. yuccae Savi f. ex Bertol. to O. hederae Duby (not to O. minor Sm.), O. centaurina Bertol. to O. litorea Guss. (not to O. artemisiae-campestris Gaudin). O. australis Moris ex Bertol., included by Beck in O. canescens C. Presl, is a good species restricted to Sardinia. O. densiflora Bertol. must not, as is customary, be ascribed to Reuter who republished it later.     

Some interesting Orthotrichum species from mainland Greece and Evvia

Abstract

Based on collections made by the authors in mainland Greece, including the Peloponnese and the island of Evvia, several Orthotrichum records of interest are documented. Orthotrichum acuminatum, O. philibertii, O. tortidontium, O . hispanicum, O. macrocephalum and O. shawii are reported for the first time from Greece, the last three also being new to the eastern Mediterranean. O. rivulare, O. scanicum, and O. alpestre, hitherto doubtfully recorded, are confirmed for Greece and new localities are given for O. stramineum, for which there are few previous records.     

THE PROBABLE ORIGIN OF ORYZOPSIS CONTRACTA

Oryzopsis contracta is found only in the Big Hollow area of southern Wyoming where it exists sympatrically with the widely distributed species O. hymenoides and O. micrantha. The three species are probably reproductively isolated from each other. Oryzopsis contracta is very similar to O. hymenoides; however, they can be separated on several characters. It also resembles O. micrantha in several characters. This suggests that O. contracta may have evolved through hybridization between the other two species. A quantitative analysis shows that O. contracta occupies an intermediate and central position between the other two species with regard to most characters analyzed. Scatter diagrams reveal a correlated deviation of O. contracta individuals from O. hymenoides toward O. micrantha with respect to several characters. Meiosis in occasional sterile O. hymenoides × O. contracta hybrids shows multivalent associations, suggesting that an appreciable part of the presumed micrantha contribution to the contracta genome was in the form of relatively large chromosome segments. The data suggest that O. contracta evolved as a result of chromosomal translocations in a chance hybrid between O. hymenoides and O. micrantha followed by backcrossing to O. hymenoides and subsequent self-fertilization of the hybrid.     

GENOME RELATIONSHIPS OF INTRA- AND INTERSECTIONAL SPECIES HYBRIDS OF ONCIDIUM TRIQUETRUM

Chromosome numbers and meiotic behavior of six interspecific hybrids of Oncidium triquetrum were investigated. The somatic chromosome number of O. triquetrum (section Oncidium) x O. variegatum (section Oncidium) was 2n = 42. O. triquetrum x O. splendidum (section Plurituberculata) and O. triquetrum x O. cebolleta (section Cebolletae) were 2n = 39 and O. triquetrum x O. floridanum (section Planilabra), O. triquetrum x O. flexuosum (section Synsepala) and O. triquetrum x O. onustum, (section Onusta) were 2n = 49. The intersectional species hybrid, O. triquetrum x O. variegatum, showed fairly regular meiosis with a mean of 20.4 bivalents, indicating strong homology of parental genomes. In contrast, highly irregular meiosis with poor chromosome pairing was observed in all intersectional hybrids. The mean number of bivalents ranged from 1.8 to 9.5. On the basis of chromosomal affinity at metaphase I, O. triquetrum showed a close relationship to O. variegatum in the same section, but more distant relationships to O. splendidum, O. cebolleta, O. floridanum, O. flexuosum and O. onustum belonging to different sections.     

Isolation of rfb Gene Clusters Directing the Synthesis of O Polysaccharides Consisting of Mannose Homopolymers and Serological Analysis of Lipopolysaccharides

Four serotypes of two genera, Escherichia coli O8 and O9 and Klebsiella O3 and O5, produce the O polysaccharides consisting of mannose homopolymers. Previously we reported the isolation and expression of E. coli O9 rfb in E. coli K-12 strains (Kido et al, J. Bacteriol., 171: 3629–3633, 1989). In this study, R' plasmids carrying his-rfb region of the other three strains were isolated and expressed in E. coli K-12 strain. Serological study of lipopolysaccharides (LPS) synthesized in E. coli K-12 strain was carried out. His-linked rfb genes from E. coli O9 and Klebsiella O3 directed the synthesis of O polysaccharides with the same antigenicity as those of the parental strains in E. coli K-12 strain. On the other hand, rfb genes from E. coli O8 and Klebsiella O5 directed the synthesis of O polysaccharides which were antigenically not identical but partially common to those of the parental strains. A rough strain derived from E. coli O8 synthesized LPS which showed the identical antigenicity as the wild strain when the his-rfb region of E. coli O8 was introduced. The results suggest that some genes located distantly from his are additionally required to complete the synthesis of O polysaccharides of E. coli O8 and Klebsiella O5.     

后蕊苣苔属花粉形态的补充研究

首次对后蕊苣苔属(Opithandra)文采后蕊苣苔(O. wentsaii)、龙南后蕊苣苔(O. burttii)和裂檐苣苔(O. pumila)的花粉进行扫描电镜研究。结果表明:三者花粉形状与外壁纹饰差异显著。在前人研究基础上,综合花粉形状及外壁纹饰特征,将后蕊苣苔属花粉分为四大类群:第一大类群包括O. burttii、O. sinohenryi、O. primuloides和O. fargesii,该类群花粉近球形,网状纹饰,网脊较宽,宽度不均匀; 第二大类群包括 O. acaulis和O. pumila,该类群花粉近球形,网状纹饰不明显,刺密且显著; 第三大类群包括O. dalzielii、O. cinerea和O. dinghushanensis,该类群花粉近球形或扁球形,网状纹饰,网脊较窄,宽度均匀; 第四大类群包括O. wentsaii和O. obtusidentata,该类群花粉长椭圆球形,网状纹饰,网脊较窄,宽度均匀。结果与王文采对该属的分类系统不完全一致,对该属分类提出一些建议。     

Wolbachia infection and an all-female trait in Ostrinia orientalis and Ostrinia zaguliaevi

Sex ratio distortion toward females (SR trait), induced by a Wolbachia bacterium, has been reported in two species of the Ostrinia furnacalis group, viz., O. furnacalis, and O. scapulalis (Lepidoptera: Crambidae). In addition, an SR trait caused by abacterial, unidentified agent(s) is known in O. scapulalis. Here we examined the SR trait in four other species of the furnacalis group, viz., O. orientalis, O. zaguliaevi, and O. zealis from Japan, and O. nubilalis from central and eastern Europe. Wolbachia infection was detected in three O. orientalis females and in one O. zaguliaevi female, and the infection was always associated with the SR trait. In terms of wsp and ftsZ gene sequences, Wolbachia strains in O. orientalis and O. zaguliaevi were indistinguishable from each other, or from those in O. furnacalis and O. scapulalis. These findings suggest that Wolbachia strains in the four Ostrinia species are probably identical. In addition, one O. zealis female, which was negative in diagnostic PCRs for Wolbachia and general bacteria, produced an all‐female brood. This trait was very similar to the SR trait caused by abacterial agent(s) in O. scapulalis.     

Genetic structure of three Oryza AA genome species (O. rufipogon, O. nivara and O. sativa) as assessed by SSR analysis on the Vientiane Plain of Laos

Microsatellite (SSR) markers can reveal a high level of polymorphic loci, and are increasingly being used in population genetic structure studies. On the Vientiane plain of Laos all components of the rice crop complex exist, wild annual (O. nivara), wild perennial (O. rufipogon) and weedy relatives of rice as well as rice itself. To understand gene flow in the rice complex, the genetic structures of O. rufipogon (10 populations), O. nivara (10 populations) and O. sativa (24 samples) from across the Vientiane Plain, Laos, were compared. Higher genetic differentiation was detected among O. nivara populations (G _ST = 0.77, R _ST = 0.71) than O. rufipogon populations (G _ST = 0.29, R _ST = 0.28), whereas genetic diversity for all populations of these two wild species showed similar values (H _T = 0.77 and 0.64 in O. rufipogon and O. nivara, respectively). Based on neighbor-joining tree constructed on the basis of genetic distance (D _A), three genetic clusters were detected, corresponding to (1) O. sativa samples, (2) O. nivara populations and (3) O. rufipogon populations. Pairwise tests confirmed the genetic differentiation of the three species. Although none of the wild rice individuals used in this study had any cultivated-specific phenotypic traits, genetic admixture analysis detected more than 10% O. sativa membership in three O. rufipogon and one O. nivara populations, indicating that O. sativa alleles may cryptically persist in natural populations of O. rufipogon and O. nivara on the Vientiane Plain.     

Observations on the fine structure of Chlamydobotrys stellata,with particular reference to its unusual chloroplast structure

Summary Eight species of Olpidium are reported from freshwater algae and from soils in Iceland. Similarities between Olpidium endogenum and O. entophytum are discussed. On the basis of the specimens at hand and the substrates in which they occur, O. zygnemicola and O. spirogyrae are reduced to synonymy with O. entophytum and O. endogenum respectively. Olpidioid fungi in Oedogonium and sterilized pine pollen are tentatively assigned to the doubtfully distinct species O. saccatum and O. utriculiforme. Olpidium pendulum, O. luxurians, and O. longicollum occur in pine pollen bait in gross water cultures of soil. These three species are only doubtfully distinct entities. Olpidium rhizophlyctidis is reported for the first time from Iceland.     

A revision of the genus Orthaea Dallas (Heteroptera: Rhyparochromidae), with the description of two new species and a new genus: Neomyocoris,to accommodate O. arnaudi Brailovsky

We redefine the genus Orthaea Dallas and redescribe O. consuta and O. procincta. Two new species are described, O. meloae from Colombia and O. montana from Peru. A new genus, Neomyocoris, is created to accommodate O. arnaudi Brailovsky. A key to the species of Orthaea and illustrations of male genitalia of O. consuta, O. procincta, O. montana and N. arnaudi n. comb. are provided. Photographs of scanning microscope and habitus are given.