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PubMed2002

Evaluation of major constraints to revegetation of lead/zinc mine tailings using bioassay techniques.

The residues from the extraction of lead/zinc (Pb/Zn) ores of most Pb/Zn mines are permanently stored in tailings ponds, which require revegetation to reduce their environmental impact. This can only be done if the main constraints on plant establishment are evaluated. This can readily be done by field and greenhouse studies. To test this, the properties of different tailings from Lechang Pb/Zn mine located at the north of Guangdong Province in southern China have been studied. Physical and chemical properties including concentrations of metals (Pb, Zn, Cd and Cu) in the tailings and soils collected from different sites have been measured. The results showed that tailings contain low nitrogen (0.016-0.075%), low-organic matter (0.58-1.78%), high salt (3.55-13.85 dS/m), and high total and diethylene-tetramine-pentaacetic acid (DTPA)-extractable metal concentrations (total: 1,019-1,642 microg g(-1) Pb, 3,078-6,773 microg g(-1) Zn, 8-23 microg g(-1) Cd, and 85-192 microg g(-1) Cu; DTPA-extractable: 59-178 microig g(-1) Pb, 21-200 microg g(-1) Zn, 0.30-1.5 mcirog g(-1) Cd, and 4.3-12 microg g(-1) Cu). Aqueous extracts of tailings/soils (10%, 20% and 30%, w/v) from different sites were prepared for testing their effects on seed germination and root elongation of a vegetable crop Brassica chinensis and a grass species Cynodon dactylon. It was found that root elongation provided a better evaluation of toxicity than seed germination. The ranking of toxicity using root elongation was: high-sulfur tailings > tailing dam > sparsely vegetated tailings > densely vegetated tailings > mountain soil for both plants. This order was consistent with DTPA-extractable Pb contents in the tailings and soils. B. chinensis seedlings were then grown in the mixtures of different proportions of tailings and farm soil for 4 weeks, and the results (dry weights of seedlings) were in line with the root elongation test. All these demonstrated that heavy metal toxicity, especially available Pb, low content of nutrient, and poor physical structure were major constraints on plant establishment and colonization on the Pb/Zn mine tailings.

Biodegradation, Environmental↗
PubMed2002

Evaluation of mine tailings effects on a benthic marine infaunal community over 29 years.

Benthic infaunal and sediment data collected over 29 years were used to examine the extent and geographic range of effects and recovery from submarine tailings deposition. Empirical data were used to determine extreme and moderate effects, and identify near-, mid- and far-field zones. A simple probability test using overlap in frequency distributions was then used to determine less obvious effects, identify "normal" or "reference" conditions, and verify the geographic range of effect zones. Tailings thickness and sediment particulate copper were elevated from the outfall to 16-20 km distant, particularly below discharge depth (50 m). Changes in tailings thickness and copper levels before, during and after mining showed three distinct impact zones below discharge depth: near-field (<5 km from outfall); mid-field (5-16 km); and far-field (20 + km). Consistent faunal declines during mining were noted at sediment particulate copper levels >300 microg g(-1), and sediment tailings thickness > 15-20 cm. Extreme impoverishment at these sediment levels were; < 100 animals/m2, <2.5 g/m2 biomass and <7 taxa per station. No stations with >300 microg g(-1) copper and 20 cm tailings had more than 40 taxa. Amphipods were particularly affected by tailings, with distributions reflecting the instability in sediments from heavy deposition and/or shifting of tailings due to resuspension. The probability testing method assumed that reference conditions existed in far-field stations. There was no difference in abundance distributions between near-, mid- and far-field zones. Total taxa per station during mining was significantly reduced (<45) in both near- and mid-field stations compared with far-field (less than 10% overlap in distributions). One midfield station in Quatsino Sound (23) was in reference condition throughout the study period. Post-closure stations in the near- and mid-field had total taxa numbers approaching far-field conditions (overlap of 62% in distributions). Within 3 years following closure, total taxa values were within the far-field range for all stations sampled. Biomass showed a distinct decline in the near-field during mining, but with more overlap in near-field and far-field distributions (27%) than for total taxa per station, and was returning to far-field conditions in the post-closure years. A multivariate (Bray-Curtis) measure of dissimilarity indicated that the near- and mid-field infaunal compositions were distinct from the far-field during mining (< 10% overlap in distributions). The mid-field composition overlapped more with the far-field in the post-closure years, but the near-field composition did not, suggesting that the mine tailings are still affecting the fauna. The most abundant taxon in each of the reference and near-field station groups both showed significantly distinct relative abundance distributions between near- and far-field stations. In summary, the probability method showed that species richness, biomass, species composition and indicator taxa were useful for differentiating affected and non-affected stations. Polychaetes recolonize stable tailings most quickly, and have dominated the tailings stations in the post-closure years. Amphipods have recolonized sporadically, but seem to be highly sensitive to tailings stability. There was no evidence of recovery in dominant bivalves or echinoderms within three years after mine closure.

Amphipoda↗
PubMed2001

Acidification of lead/zinc mine tailings and its effect on heavy metal mobility.

The acid-forming potential of lead/zinc (Pb/Zn) mine tailings at Lechang City of Guangdong Province was studied using both net acid generation (NAG) and acid-base accounting (ABA) methods. The pyritic and total sulfur contents of the tailings were 12.6% and 18.7%, respectively. The mean acid neutralization capacity (ANC) was 63.5 kg H2SO4/t while three oxidized tailings samples had an ANC less than zero. The NAG and net acid production potential (NAPP) values were 220 and 326 kg H2SO4/t, and both the NAG and NAPP results indicated that the tailings had a high acid-forming potential. NAG was more accurate than NAPP in predicting acid-forming potential of the tailings due to uncompleted oxidization of pyritic sulfur. Analysis of samples from two profile tests indicated that acidification mainly occurred at the surface (0-20 cm) and had little effects at deep layer of the tailings. Total concentrations of Pb, Zn, Cu, and Cd were increased greatly with depth at the acidified tailings profile, while heavy metal concentrations at different depths of nonacidified tailings profile were similar. The results indicated that depletion of heavy metals at the acidified surface was due to acidification. The diethylenetetramine pentaacetic acid (DTPA)-extractable Pb, Zn, Cu, and Cd concentrations of acidified tailings surface (0-20 cm) were significantly higher than those of nonacidified tailings, which further revealed that acidification enhanced the mobility of heavy metals in the tailings.

Forecasting↗
PubMed2001

NMR analysis of structure and dynamics of the cytosolic tails of integrin alpha IIb beta 3 in aqueous solution.

The structural and dynamic properties of the cytosolic tails of the adhesion receptor integrin alphaIIbbeta3, fused to a coiled-coil construct via (Gly)(3) linkers, were studied in aqueous solution by nuclear magnetic resonance (NMR) spectroscopy. Both tails were largely flexible and unstructured, although, in the beta3 tail, residues Arg(724)-Ala(735) have a propensity to form a helical structure and residues Asn(744)-Tyr(747) (NPLY) have a propensity to adopt reverse-turn conformations. The mutation beta3(Y747A) disrupted this reverse-turn tendency and markedly reduced the affinity of the head domain of the cytoskeletal protein, talin for the beta3 tail. Omission of the (Gly)(3) linker connecting the coiled-coiled helices and the integrin tails lead to helix propagation into the beta3 tail extending up to eight residues. A variety of different tail constructs were made and studied to reveal tail-tail interactions, but surprisingly no significant interactions between both tails could be detected within the context of our constructs. These results provide structural insight into a highly conserved beta tail motif (NPXY/F) required for integrin signaling and highlight a second transiently structured region (residues Arg(724)-Ala(735)), which might also be of functional significance.

Amino Acid Sequence↗
PubMed1995

Poly(A) tail length control is caused by termination of processive synthesis.

Poly(A) polymerase synthesizes poly(A) tails rapidly and processively only when the substrate RNA is bound simultaneously by two stimulatory proteins, the cleavage and polyadenylation specificity factor (CPSF) and poly(A)-binding protein II (PAB II). A burst of synthesis terminates after the addition of about 250 nucleotides, a length corresponding to that of newly synthesized poly(A) tails in vivo. Further elongation is slow. Length control can be reproduced with premade poly(A) tails of different lengths and is insensitive to large changes in the elongation rate. Thus, the control mechanism truly measures the length of the poly(A) tail. The stimulatory action of PAB II is similar on long and short tails. Coating of poly(A) with one PAB II molecule for approximately 30 nucleotides is required, such that the number of PAB II molecules in the polyadenylation complex is a direct measure of poly(A) tail length. CPSF also stimulates poly(A) polymerase on long and short tails. Long tails differ from short ones only in that they do not permit the simultaneous stimulation of poly(A) polymerase by CPSF and PAB II. Consequently, elongation of long tails is distributive. Thus, length control is brought about by an interruption of the interactions responsible for rapid and processive elongation of short tails. The 3'-end of the poly(A) tail is not sequestered in the protein-RNA complex when the correct length has been reached. Neither ATP hydrolysis nor turnover of the polymerized AMP is involved in length control.

Adenosine Triphosphate↗
PubMed2002

Active Alu element "A-tails": size does matter.

Long and short interspersed elements (LINEs and SINEs) are retroelements that make up almost half of the human genome. L1 and Alu represent the most prolific human LINE and SINE families, respectively. Only a few Alu elements are able to retropose, and the factors determining their retroposition capacity are poorly understood. The data presented in this paper indicate that the length of Alu "A-tails" is one of the principal factors in determining the retropositional capability of an Alu element. The A stretches of the Alu subfamilies analyzed, both old (Alu S and J) and young (Ya5), had a Poisson distribution of A-tail lengths with a mean size of 21 and 26, respectively. In contrast, the A-tails of very recent Alu insertions (disease causing) were all between 40 and 97 bp in length. The L1 elements analyzed displayed a similar tendency, in which the "disease"-associated elements have much longer A-tails (mean of 77) than do the elements even from the young Ta subfamily (mean of 41). Analysis of the draft sequence of the human genome showed that only about 1000 of the over one million Alu elements have tails of 40 or more adenosine residues in length. The presence of these long A stretches shows a strong bias toward the actively amplifying subfamilies, consistent with their playing a major role in the amplification process. Evaluation of the 19 Alu elements retrieved from the draft sequence of the human genome that are identical to the Alu Ya5a2 insert in the NF1 gene showed that only five have tails with 40 or more adenosine residues. Sequence analysis of the loci with the Alu elements containing the longest A-tails (7 of the 19) from the genomes of the NF1 patient and the father revealed that there are at least two loci with A-tails long enough to serve as source elements within our model. Analysis of the A-tail lengths of 12 Ya5a2 elements in diverse human population groups showed substantial variability in both the Alu A-tail length and sequence homogeneity. On the basis of these observations, a model is presented for the role of A-tail length in determining which Alu elements are active.

3' Flanking Region↗
PubMed1990

Effects of intrathecal substance P and a substance P antagonist on a reflex to noxious heat are independent of changes in tail skin temperature.

Substance P or the substance P receptor antagonist (D-Arg1,D-Trp7.9,Leu11)-substance P (Spantide) was injected into the lumbar subarachnoid space in mice, and the ability to change the tail-flick reflex and the tail skin temperature was investigated. Tail-flick latency (the time needed to evoke the tail-flick reflex by noxious radiant heat) was reduced for 1-4 min after intrathecal administration of substance P (5 micrograms), but the tail skin temperature was not significantly changed. Nor was the tail skin temperature significantly changed after intrathecal injection of Spantide (5 micrograms), but this compound significantly increased tail-flick latencies 5-30 min after injection. Analysis of co-variance showed that the effects of substance P or Spantide on tail-flick latency were significant, whereas the influence of tail skin temperature on tail-flick latency was non-significant. Thus, intrathecal substance P induces a short-lasting increase in nociceptive sensitivity, and intrathecal Spantide produces an antinociceptive effect of longer duration. The results seem not to be the result of changes in tail skin temperature.

Animals↗
PubMed1998

Measles viruses with altered envelope protein cytoplasmic tails gain cell fusion competence.

The cytoplasmic tail of the measles virus (MV) fusion (F) protein is often altered in viruses which spread through the brain of patients suffering from subacute sclerosing panencephalitis (SSPE). We transferred the coding regions of F tails from SSPE viruses in an MV genomic cDNA. Similarly, we constructed and transferred mutated tail-encoding regions of the other viral glycoprotein hemagglutinin (H) gene. From the mutated genomic cDNAs, we achieved rescue of viruses that harbor different alterations of the F tail, deletions in the membrane-distal half of the H tail, and combinations of these mutations. Viruses with alterations in any of the tails spread rapidly through the monolayer via enhanced cell-cell fusion. Double-tail mutants had even higher fusion competence but slightly decreased infectivity. Analysis of the protein composition of released mutant viral particles indicated that the tails are necessary for accurate virus envelope assembly and suggested a direct F tail-matrix (M) protein interaction. Since even tail-altered glycoproteins colocalized with M protein in intracellular patches, additional interactions may exist. We conclude that in MV infections, including SSPE, the glycoprotein tails are involved not only in virus envelope assembly but also in the control of virus-induced cell fusion.

Amino Acid Sequence↗
PubMed2000

Host protein interactions with the 3' end of bovine coronavirus RNA and the requirement of the poly(A) tail for coronavirus defective genome replication.

RNA viruses have 5' and 3' untranslated regions (UTRs) that contain specific signals for RNA synthesis. The coronavirus genome is capped at the 5' end and has a 3' UTR that consists of 300 to 500 nucleotides (nt) plus a poly(A) tail. To further our understanding of coronavirus replication, we have begun to examine the involvement of host factors in this process for two group II viruses, bovine coronavirus (BCV) and mouse hepatitis coronavirus (MHV). Specific host protein interactions with the BCV 3' UTR [287 nt plus poly(A) tail] were identified using gel mobility shift assays. Competition with the MHV 3' UTR [301 nt plus poly(A) tail] suggests that the interactions are conserved for the two viruses. Proteins with molecular masses of 99, 95, and 73 kDa were detected in UV cross-linking experiments. Less heavily labeled proteins were also detected in the ranges of 40 to 50 and 30 kDa. The poly(A) tail was required for binding of the 73-kDa protein. Immunoprecipitation of UV-cross-linked proteins identified the 73-kDa protein as the cytoplasmic poly(A)-binding protein (PABP). Replication of the defective genomes BCV Drep and MHV MIDI-C, along with several mutants, was used to determine the importance of the poly(A) tail. Defective genomes with shortened poly(A) tails consisting of 5 or 10 A residues were replicated after transfection into helper virus-infected cells. BCV Drep RNA that lacked a poly(A) tail did not replicate, whereas replication of MHV MIDI-C RNA with a deleted tail was detected after several virus passages. All mutants exhibited delayed kinetics of replication. Detectable extension or addition of the poly(A) tail to the mutants correlated with the appearance of these RNAs in the replication assay. RNAs with shortened poly(A) tails exhibited less in vitro PABP binding, suggesting that decreased interactions with the protein may affect RNA replication. The data strongly indicate that the poly(A) tail is an important cis-acting signal for coronavirus replication.

3' Untranslated Regions↗
PubMed2006

Mixing of propagules from discrete sources at long distance: comparing a dispersal tail to an exponential.

BACKGROUND: Rare long distance dispersal events impact the demography and the genetic structure of populations. When dispersal is modelled via a dispersal kernel, one possible characterisation of long-distance dispersal is given by the shape of the tail of the kernel, i.e. its type of decay. This characteristic is known to directly act on the speed and pattern of colonization, and on the spatial structure of genetic diversity during colonization. In particular, colonization waves behave differently depending on whether the kernel decreases faster or slower than an exponential (i.e. is thin-tailed vs. fat-tailed). To interpret and extend published results on the impact of long-distance dispersal on the genetic structure of populations, we examine a classification of dispersal kernels based on the shape of their tails and formally demonstrate qualitative differences among them that can influence the predicted diversity of a propagule pool sampled far from two distinct sources. RESULTS: We show that a fat-tailed kernel leads asymptotically to a diverse propagule pool containing a balanced mixing of the propagules from the two sources, whereas a thin-tailed kernel results in all propagules originating from the closest source. We further show that these results hold for biologically relevant distances under certain circumstances, and in particular if the number of propagules is large enough, as would be the case for pollen or seeds. CONCLUSION: To understand the impact of long-distance dispersal on the structure and dynamics of a metapopulation, it might be less important to precisely estimate an average dispersal distance than to determine if the tail of the dispersal kernel is fatter or thinner than that of an exponential function. Depending solely on this characteristic, a metapopulation will behave similarly to an island model with a diverse immigrant pool or to a stepping-stone model with migrants from closest populations. Our results further help to understand why thin-tailed dispersal kernels lead to a colonization wave of constant speed, whereas fat-tailed dispersal kernels lead to a wave of increasing speed. Our results also suggest that the diversity of the pollen cloud of a mother plant should increase with increasing isolation for fat-tailed kernels, whereas it should decrease for thin-tailed kernels.

Demography↗
PubMed1994

Vimentin's tail interacts with actin-containing structures in vivo.

The tail domain of the intermediate filament (IF) protein vimentin is unnecessary for IF assembly in vitro. To study the role of vimentin's tail in vivo, we constructed a plasmid that directs the synthesis of a 'myc-tagged' version of the Xenopus vimentin-1 tail domain in bacteria. This polypeptide, mycVimTail, was purified to near homogeneity and injected into cultured Xenopus A6 cells. In these cells the tail polypeptide co-localized with actin even in the presence of cytochalasin. Two myc-tagged control polypeptides argue for the specificity of this interaction. First, a similarly myc-tagged lamin tail domain localizes to the nucleus, indicating that the presence of the myc tag did not itself confer the ability to co-localize with actin (Hennekes and Nigg (1994) J. Cell Sci. 107, 1019-1029). Second, a myc-tagged polypeptide with a molecular mass and net charge at physiological pH (i.e. -4) similar to that of the mycVimTail polypeptide, failed to show any tendency to associate with actin-containing structures, indicating that the interaction between mycVimTail and actin-containing structures was not due to a simple ionic association. Franke (1987; Cell Biol. Int. Rep. 11, 831) noted a similarity in the primary sequence between the tail of the type I keratin DG81A and vimentin. To test whether the DG81A tail interacted with actin-containing structures, we constructed and purified myc-tagged DG81A tail polypeptides. Unexpectedly, these keratin tail polypeptides were largely insoluble under physiological conditions and formed aggregates at the site of injection. While this insolubility made it difficult to determine if they associated with actin-containing structures, it does provide direct evidence that the tails of vimentin and DG81A differ dramatically in their physical properties. Our data suggest that vimentin's tail domain has a highly extended structure, binds to actin-containing structures and may mediate the interaction between vimentin filaments and microfilaments involved in the control of vimentin filament organization (Hollenbeck et al. (1989) J. Cell Sci. 92, 621; Tint et al. (1991) J. Cell Sci. 98, 375).

Actins↗
PubMed1990

Differences in inositol phosphate production in rat tail artery and thoracic aorta.

Pharmacomechanical coupling of vascular smooth muscle is believed to be mediated by inositol trisphosphate (IP3). Numerous studies have demonstrated an increase in inositol phosphates following tissue stimulation using either intact aortic strips or cultured cells from aorta. However, little information is available concerning inositol phosphates in vascular tissue other than in the large conduit vessel, the aorta. This present study was designed to examine the role of inositol phosphate metabolism following adrenergic stimulation of the muscular rat tail artery as compared to the aorta. Segments of thoracic aorta and tail artery from male Sprague Dawley rats were labeled with [3H]inositol and stimulated with norepinephrine. The norepinephrine concentration that resulted in a half-maximal stimulation of inositol phosphates was approximately 10(-6) M in both the aorta and tail artery. Although the sensitivity of the two vessels to norepinephrine stimulation were similar, the stimulated levels of IP, IP2, and IP3 were from 1 to 2 orders of magnitude greater in the tail artery than in aorta. IP production in aorta and tail artery was a linear function of time (from 0 to 30 min). Significant levels of IP3 (the 1,4,5-IP3 isomer as determined by HPLC) could only be detected in the tail artery and appeared to be produced optimally after 5 min of stimulation. The several order of magnitude increase in adrenergic stimulated inositol phosphate production in the tail artery was not due to either an increased magnitude of [3H]inositol incorporated into PI, PIP, and PIP2 or to a greater percentage of smooth muscle cells per unit tissue of the rat tail artery. We believe the results of this study demonstrate that the increased inositol phosphate metabolism in the vascular smooth muscle cells of the tail artery is an intrinsic property of the cell. Moreover, due to the significant levels of all inositol phosphates produced in the tail artery, this muscular artery may be a better model, as compared to the aorta, for future studies investigating pharmacomechanical coupling of vascular smooth muscle.

Animals↗
PubMed2005

Tail loss, body condition and swimming performances in tiger snakes, Notechis ater occidentalis.

In limbless tetrapods such as snakes, propulsive forces are generated by lateral undulations of the body and of the tail. In a large population of tiger snakes from Western Australia, tail loss was extremely common (58% of the individuals) and often very severe (more than two-thirds of the tail was missing in 14% of the cases, and in some instances, the tail was totally lost). Tail loss was not however correlated with body size, mass or body condition of wild individuals, and hence did not influence their abilities to acquire resources. These large venomous snakes exhibit marked aquatic habits. Locomotor tests in controlled conditions revealed that tail loss had a significant negative influence on burst swimming performances. However, no effect was found on routine swimming speed and total distance travelled over 5 min. These results suggest that a long and slender tail, although important for maximal speed, is not necessarily relevant for the locomotor abilities required for successful hunting. Tail-damaged individuals outnumbered intact snakes, suggesting that tail loss did not severely compromise survival. Overall, in this species, a slight deterioration of maximal speed due to severe tail loss probably has a low (undetectable) ecological impact, at least for adults.

Animals↗
PubMed1977

Multi-tailed spermatozoa in a case with asthenospermia and teratospermia.

A case is presented of an infertile male whose spermatozoa showed low mobility, a high percentage of irregular large heads and a variable number of tails (between 0 and 4). In the spermatozoa with several tails each axoneme, surrounded by its own outer fibres and mitochondrial sheath, arose from its own basal plate. Throughout the middle piece of every spermatozoon all the axonemes were arranged in parallel and were enclosed by the same plasma membrane. Usually, at the beginning of the principal piece, the axonemes became separated. At this level each of them constituted a different tail. In most spermatozoa the fine structure of the tail or tails was normal. The alterations of the inner structure of the tail or tails was normal. The alterations of the inner structure of the flagellum observed in some spermatozoa (enlargement of the fibrous sheath, duplication of the outer fibres and of some peripheral doublets) were independent of the number of tails present. In some cases, an intracytoplasmic coiling of the tail or tails could be observed.

Adult↗
PubMed1997

Role of central nicotinic and beta-adrenergic receptors in the onset and further development of tail-tremor induced by repeated nicotine administration to rats.

The effects of nicotinic and beta-adrenergic receptor antagonists on tail-tremor induced by repeated nicotine administration were investigated in rats. The daily administration of nicotine (0.5 mg/kg/day, s.c.) for 8 days resulted in an augmentation of tail-tremor. However, repeated administration of dimethyl phenyl piperazinium iodide (1 mg/kg/day, s.c.) for 8 days did not cause tail-tremor. Mecamylamine (0.5 mg/kg, i.p), administered before the nicotine injection on each day, abolished the tail-tremor. After discontinuation of the mecamylamine treatment, nicotine injections caused tail-tremor augmentation. Propranolol (20 mg/kg, i.p.), administered before the nicotine on each day, suppressed the appearance of tail-tremor. After the discontinuation of propranolol treatment, the degree of tail-tremor induced by a single injection of nicotine on day 9 was much greater in the propranolol-treated group than in the saline-treated control group. Neither carteolol (20 mg/kg, i.p.) nor metoprolol (20 mg/kg, i.p.) treatment showed such effects. Intraspinal injection of 6-hydroxydopamine markedly enhanced the tail-tremor induced on the first day of nicotine injection. This effect became more intense on subsequent administration of nicotine. The enhanced tail-tremor following 6-hydroxydopamine treatment was abolished by mecamylamine (0.5 and 1 mg/kg, i.p.), and was suppressed by propranolol (5-20 mg/kg, s.c.) in a dose-dependent manner. These results suggest that central nicotinic receptors are essential for the onset and for the further development of tail-tremor induced by the repeated administration of nicotine, and that beta 2-adrenoceptors are associated with the tremor mechanism. Moreover, spinal noradrenergic mechanisms may be involved in the manifestation of this phenomenon.

Adrenergic Agents↗
PubMed1998

Tail and eye movements evoked by electrical microstimulation of the optic tectum in goldfish.

This work studies the tail and eye co-ordinated movements evoked by the focal electrical stimulation of the tectum in goldfish. The aim of the study is to understand better those tectal sites and mechanisms that either remain functionally unaltered or are adaptively modified across vertebrates. Stimulation was applied in various tectal zones, and the characteristics of evoked tail and eye movements were examined as a function of the stimulation site over tectal surface and the stimulus parameters. Two types of response were electrically evoked: the former turned the body and the eyes contraversively towards the source of natural stimulus; the second produced initial ipsiversive turning of the body and eyes, followed by several tail beats. Evoking one or other response depended on both the site and parameters of stimulation, and responses were interpreted as orienting- and escape-like, respectively. Depending on the stimulation site, four different zones in the tectum were distinguished: in the medial zone the stimulus elicited eye and tail movements whose size increased with the distance to the rostral pole. The stimulation of the antero-medial zone evoked contraversive or ipsiversive eye saccades but tail movements were similar, irrespective of eye movements. Stimulation within the extreme antero-medial zone evoked convergent eye movements, and tail displacements turning the body either ipsiversively or contraversively. Stimulation of the posterior zone often evoked complex tail movements and pure horizontal eye saccades. Both orienting- and escape-like responses were also dependent on the stimulus parameters. The relationships between stimulus parameters and tail- and eye-orienting movement characteristics suggest that the velocity and duration might be encoded in different aspects of the tectal activity. Current strength also modified the number of tail beats that appeared during escape-like response. In conclusion, the present data suggest the involvement of the optic tectum not only in orienting but also in escape responses and that movements of eye and tail mediating such responses depend on the tectal active locus together with its level of activity.

Animals↗
PubMed1990

Agonist action at 5-HT1C receptors facilitates 5-HT1A receptor-mediated spontaneous tail-flicks in the rat.

In rats lightly restrained in plastic cylinders, subcutaneous administration of the selective, high efficacy 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), induced spontaneous tail-flicks, that is, tail-flicks in the absence of extraneous stimulation. The putative 5-HT1B receptor agonist, CGS 12066B, the mixed 5-HT1B/1C receptor agonists, 1-((3-(trifluoromethyl)phenyl]piperazine (TFMPP) and 1-(3-chlorophenyl)piperazine (mCPP), the 5-HT1C/2 receptor agonist, [+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) and the 5-HT1B/1C/2 receptor agonist, quipazine, did not, in contrast, elicit tail-flicks when applied alone. However, TFMPP, mCPP, DOI and quipazine, but not CGS 12066B, each potentiated the action of 8-OH-DPAT. Further, in the presence of TFMPP, mCPP and DOI, the dose-response curve for the induction of tail-flicks by 8-OH-DPAT was both steeper and shifted to the left. Tail-flicks induced by another high efficacy 5-HT1A receptor agonist, lisuride, were also enhanced by TFMPP, mCPP and DOI. The 5-HT1A receptor partial agonists, buspirone and (+/-)-flesinoxan, evoked tail-flicks only in the presence of TFMPP, mCPP or DOI. The mixed 5-HT1C/2 receptor antagonists, ritanserin and ICI 169,369, did not modify the action of 8-OH-DPAT alone but abolished the potentiation of 8-OH-DPAT-induced tail-flicks by DOI and TFMPP. Further, the selective 5-HT1A receptor antagonist, BMY 7378, blocked tail-flicks induced by both 8-OH-DPAT alone and 8-OH-DPAT plus DOI or TFMPP. A common property of those drugs potentiating 8-OH-DPAT-induced tail-flicks is an agonist action at 5-HT1C receptors and the data indicate that it is this mechanism which underlies the facilitation of tail-flicks.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1996

Acute and repeated activation of male sexual behavior by tail pinch: opioid and dopaminergic mechanisms.

We studied the effect of tail pinch on male sexual behavior and its neurochemical basis. Male rats were gonadectomized and maintained on low doses of testosterone propionate (20.0 micrograms/day). Tail pinch significantly increased the percentage of males that mounted, intromitted, and ejaculated within a 30-min test, and these increases were attenuated by both pimozide (1.0 mg/kg, i.p.) and by naloxone (0.5, 1.0, and 2.0 mg/kg, s.c.). Moreover, tail pinch in the presence of an estrous female led to significantly increased female-directed behavior 48 h later during a test without tail pinch. Repeated tail pinch tests led to progressively more sexual activity, and the development of this behavioral sensitization was prevented by naloxone. These findings suggest that tail pinch increases the salience of the incentive characteristics of the female. Furthermore, during subsequent tests, with or without tail pinch, the increased salience of the female remains, as measured by the continued increases in sexual activity. These acute and sensitized behavioral increases might result from tail pinch-induced activation of the midbrain dopamine system via an opioid mechanism; either preventing tail pinch-induced dopamine activation (by an opioid antagonist) or blocking the effects of dopamine activation (by a dopamine antagonist) attenuated the long-term facilitation of sexual behavior seen after pairing the female with tail pinch.

Animals↗