scholarly journals Transposition Pattern of the Maize Element Ac from the Bz-M2(ac) Allele.

Genetics ◽  
1989 ◽  
Vol 122 (2) ◽  
pp. 447-457 ◽  
Author(s):  
H K Dooner ◽  
A Belachew
Keyword(s):  
Donor Site ◽  
Receptor Site ◽  
Receptor Sites ◽  
Mutable Allele ◽  
Ac Transposition ◽  
P Locus

Abstract The pattern of transposition of Ac from the mutable allele bz-m2(Ac) has been investigated. Stable (bz-s) and finely spotted (bz-m(F)) exceptions were selected from coarsely spotted bz-m2(Ac) ears. The presence or absence of a transposed Ac (trAc) in the genome was determined and, when present, the location of the trAc was mapped relative to the flanking markers sh and wx. The salient general features of Ac transposition to sites linked to bz are that the receptor sites tend to be clustered on either side of the bz donor site and that transposition is bidirectional and nonpolar. Thus, the symmetrical clustering in the distribution of receptor sites adjacent to bz differs from the asymmetrical clustering reported in 1984 for the P locus by I. M. GREENBLATT. Though Ac tends to transpose preferentially to closely linked sites, an appreciable fraction of Ac transpositions from bz-m2(Ac) is to unlinked sites: 41% among bz-s derivatives and 59% among bz-m(F) derivatives. Many transposition events among the bz-m(F) selections result in kernels carrying a genetically noncorresponding embryo. These can be interpreted as twin sectors arising at one of the megagametophytic mitoses. The bz locus data fit the earlier (1962) model of I. M. GREENBLATT and R. A. BRINK in which transposition takes place from a replicated donor site to either an unreplicated or replicated receptor site.

A CHROMOSOME REPLICATION PATTERN DEDUCED FROM PERICARP PHENOTYPES RESULTING FROM MOVEMENTS OF THE TRANSPOSABLE ELEMENT, MODULATOR, IN MAIZE

Genetics ◽  
1984 ◽  
Vol 108 (2) ◽  
pp. 471-485 ◽  
Author(s):  
Irwin M Greenblatt
Keyword(s):  
Transposable Element ◽  
Receptor Site ◽  
Initiation Site ◽  
Chromosome Replication ◽  
Chromosome 1 ◽  
Replication Pattern ◽  
Receptor Sites ◽  
P Locus

ABSTRACT Modulator (Mp) was mapped after it transposed from the P locus on chromosome 1 by studying 105 light variegated/red twin sectors on medium variegated pericarp ears. Sixty-one percent of the receptor sites were detectably linked to P, and these showed an asymmetry of distribution adjacent to P. No transpositions were mapped in the 4 map units proximal to P, whereas 23 cases mapped to the same length distal to P. The remaining transpositions of Mp on chromosome 1, both proximal and distal to P, were equally scattered. It has previously been shown that when Modulator transposes it replicates at the P locus and a second time at the receptor site. The pattern of transposition adjacent to P is consistent with a hypothesis that a replicon initiation site is situated proximal to P; that Modulator transposes at the time of replication; that it is not able to transpose into a replicated region but only into a replicating one. No difference in distribution of receptor sites was found when the Modulator was detected vs. not detected in the red co-twins by testing with a Dissociation element.

scholarly journals Dopamine receptor sites in the anterior pituitary.

1979 ◽  
Vol 27 (8) ◽  
pp. 1205-1207 ◽  
Author(s):  
P C Goldsmith ◽  
M J Cronin ◽  
R I Weiner
Keyword(s):  
Dopamine Receptors ◽  
Dopamine Receptor ◽  
Anterior Pituitary ◽  
Receptor Site ◽  
Cell Types ◽  
Pituitary Cells ◽  
Vesicle Membrane ◽  
Receptor Sites ◽  
Immunocytochemical Method ◽  
Potent Antagonist

An immunocytochemical method was developed to visualize dopamine receptor sites on dispersed anterior pituitary cells of the rat. Dopamine receptors were labeled with the antagonist haloperidol. Some cells were incubated with haloperidol and a 100-fold excess of the potent antagonist D-butaclamol to determine nonspecific binding. The labeled sites were stained with an antibody against haloperidol and the peroxidase anti-peroxidase (PAP) technique. PAP complexes which served as markers for dopamine binding sites appeared on the outer plasmalemmal surface of the vast majority of mammotrophs. PAP complexes attached to the inner surface of endocytotic vesicle membrane suggested internalization of receptor-rich portions of the plasmalemma. Some gonadotrophs and somatotrophs were specifically stained to a lesser extent. However, high receptor site density and internalization of PAP complexes were never observed on cell types other than mammotrophs. The presence of dopamine receptors on the plasmalemma of mammotrophs provides strong additional evidence that dopamine acts upon these cells as a prolactin inhibitory hormone.

scholarly journals Evaluating mitigation translocations for better biodiversity outcomes

2021 ◽  
Author(s):  
◽  
Sydney Dean
Keyword(s):  
Body Condition ◽  
Site Selection ◽  
Urban Areas ◽  
Selection Criteria ◽  
National Level ◽  
Receptor Site ◽  
Biodiversity Loss ◽  
Receptor Sites ◽  
Resident Populations

<p>The expansion of urban areas and associated loss of natural areas due to development are greatly contributing to global biodiversity loss. Furthermore, development produces direct harm to wildlife and their habitat. In New Zealand, lizards and their habitat are legally protected and damage due to development of a natural area must be avoided or mitigated whenever possible. Mitigation translocations, the intentional relocation of individuals from the site to be developed to a receptor site, have become commonly used to meet legal obligations; however, mitigation translocations do not guarantee survival of individuals or population success at the receptor site. I aimed to evaluate the success of a mitigation translocation case study, proactively plan receptor sites for a mitigation translocation, and develop a framework for selecting and preparing receptor sites to provide better mitigation translocation outcomes, particularly for herpetofauna. I evaluated the short-term success of a mitigation translocation case study using results from post-release monitoring at receptor sites. This is one of the first studies to provide multiple post-release monitoring sessions and detail recapture rates and body condition changes of lizards at receptor sites with and without resident populations following mitigation translocation. I expanded upon commonly used receptor site selection criteria and translocation data management systems by proactively studying and preparing receptor sites in regional parks, including conducting pilot surveys to evaluate resident populations. Recapture rates were similar between receptor sites (9% and 11.8%) and the limited number of recaptured individuals showed an increase in body condition from the time of salvage to intervals of one- and two-years post-release. Presence of residents was not found to have an effect on recapture rates or body condition changes. Implementation of enhanced site selection criteria resulted in approval of six sites within three protected areas for future mitigation translocations. These sites had low numbers of resident lizards present, if at all. A geodatabase was developed to store results from receptor site evaluations before and after translocation. Together, the improved criteria and geodatabase fit into a framework for selecting and preparing receptor sites to improve outcomes of mitigation translocations of herpetofauna. The framework produced has potential to be used at a national level, in collaboration with ecologists, iwi, and community groups, and for a variety of species. Mitigation translocations should be re-evaluated as the go-to method to mitigate damage to lizards due to development; however, if they must continue, it is essential that best practices are used, and results are published so that outcomes can improve for biodiversity.</p>

scholarly journals Stereospecificity of multiple receptor sites in a labellar sugar receptor of the fleshfly for amino acids and small peptides.

1981 ◽  
Vol 77 (1) ◽  
pp. 23-39 ◽  
Author(s):  
I Shimada ◽  
T Tanimura
Keyword(s):  
Amino Acids ◽  
Functional Group ◽  
Decisive Role ◽  
Receptor Site ◽  
Small Peptides ◽  
Hydrogen Bond Formation ◽  
Similar Treatment ◽  
Sugar Receptor ◽  
Receptor Sites ◽  
Multiple Receptor

N-Formylation and N-methylation of the alpha-amino group of L-phenylalanine result in extremely decreased responses of the labellar sugar receptor of the fleshfly, whereas the same structural alteration of L-valine hardly affects the response. Methyl esterification of the alpha-carboxyl group of phenylalanine, on the other hand, maintains the response to some extent, but similar treatment of valine completely diminishes the response. The aromatic structure in phenylalanine is not essential for stimulation. These results suggest a substantial difference in the stereospecificities and functional group specificities of the furnase (F) and aliphatic carboxylate (T) sites in the sugar receptor. The effect of small peptides on the sugar receptor was examined systematically. Their effectiveness depends mainly on the place of the constituent amino acids rather than on their composition, indicating the decisive role that certain aliphatic amino acids in the C-terminal position play in stimulation. Remarkable regularities in the stimulating effectiveness of small peptides exactly correspond to the stereospecificity of each receptor site. We propose two hypothetical models of the F and T sites, which involve three and two subsites, respectively, that are capable of hydrogen bond formation. The F and T sites also have a hydrophobic subsite that discriminates the R groups of the stimulants and a few spatial barriers.

scholarly journals Displacement of One Drug by Another from Carrier or Receptor Sites

1965 ◽  
Vol 58 (11P2) ◽  
pp. 946-955 ◽  
Author(s):  
Bernard B Brodie
Keyword(s):  
Sympathetic Nerve ◽  
Dynamic Equilibrium ◽  
Extracellular Fluid ◽  
Receptor Site ◽  
Biologically Active ◽  
Nerve Endings ◽  
Intrinsic Activity ◽  
Unbound Fraction ◽  
Receptor Sites ◽  
Almost All

The medium of drug transfer is the water of plasma and extracellular fluid. Without complicating factors, the level of drug at a receptor site would be equal to that in the tissues and in plasma, and in dynamic equilibrium. Actually, almost all drugs are reversibly bound to proteins in plasma or tissue. The bound drug, often a high proportion of the total, acts as a reservoir, preventing wild fluctuations between ineffective and toxic levels of the biologically active unbound fraction. Displacement from a receptor site diminishes drug activity, but displacement from plasma or tissue proteins augments the effect by making more unbound drug available at the receptor site. Atropine has no intrinsic activity, but displaces acetylcholine or pilocarpine from receptors at para-sympathetic nerve endings. Similarly guanethidine competes with noradrenaline at sympathetic nerve endings, but in turn is displaced by amphetamine-like drugs. Many acidic drugs (phenylbutazone, sulfonamides, coumarin anticoagulants, salicylates, &c.) are highly bound to one or two sites on albumin molecules. When the limited carrying capacity of the plasma proteins is filled, any unbound surplus is usually soon metabolized or excreted, so the plasma level becomes restabilized. Meanwhile, however, there may be dramatic effects such as hypoglycemia, when sulfonamides are given to patients on tolbutamide, or bleeding when phenylbutazone is given to patients on warfarin. Although hormones, like thyroxine, insulin and cortisol, are carried by specific proteins, they too can be displaced. All the antirheumatic drugs so far examined have displaced cortisol and presumably driven it into tissues. This may be one mechanism of action. Possibly the sulfonylurea drugs act by displacing insulin from proteins in the pancreas, plasma or elsewhere.

scholarly journals Biphasic regulation of development of the high-affinity saxitoxin receptor by innervation in rat skeletal muscle.

1982 ◽  
Vol 80 (5) ◽  
pp. 753-768 ◽  
Author(s):  
S J Sherman ◽  
W A Catterall
Keyword(s):  
Skeletal Muscle ◽  
Subsequent Development ◽  
Receptor Site ◽  
Triceps Surae ◽  
Second Phase ◽  
Adult Density ◽  
Rat Skeletal Muscle ◽  
High Affinity ◽  
Site Density ◽  
Receptor Sites

Specific binding of 3H-saxitoxin (STX) was used to quantitate the density of voltage-sensitive sodium channels in developing rat skeletal muscle. In adult triceps surae, a single class of sites with a KD = 2.9 nM and a density of 21 fmol/mg wet wt was detected. The density of these high-affinity sites increased from 2.0 fmol/mg wet wt to the adult value in linear fashion during days 2-25 after birth. Denervation of the triceps surae at day 11 or 17 reduced final saxitoxin receptor site density to 10.4 or 9.2 fmol/mg wet wt, respectively, without changing KD. Denervation of the triceps surae at day 5 did not alter the subsequent development of saxitoxin receptor sites during days 5-9 and accelerated the increase of saxitoxin receptor sites during days 9-13. After day 13, saxitoxin receptor development abruptly ceased and the density of saxitoxin receptor sites declined to 11 fmol/wg wet wt. These results show that the regulation of high-affinity saxitoxin receptor site density by innervation is biphasic. During the first phase, which is independent of continuing innervation, the saxitoxin receptor density increases to 47-57% of the adult level. After day 11, the second phase of development, which is dependent on continuing innervation, gives rise to the adult density of saxitoxin receptors.

Inhibition of Presynaptic Sodium Channels by Halothane 

1998 ◽  
Vol 88 (4) ◽  
pp. 1043-1054 ◽  
Author(s):  
Lingamaneni Ratnakumari ◽  
Hugh C. Hemmings
Keyword(s):  
Radioligand Binding ◽  
Glutamate Release ◽  
Receptor Site ◽  
Na Channel ◽  
Na Channels ◽  
General Anesthetic ◽  
Adult Rat ◽  
Anesthetic Agents ◽  
Receptor Sites ◽  
Channel Dependent

Background Recent electrophysiologic studies indicate that clinical concentrations of volatile general anesthetic agents inhibit central nervous system sodium (Na+) channels. In this study, the biochemical effects of halothane on Na+ channel function were determined using rat brain synaptosomes (pinched-off nerve terminals) to assess the role of presynaptic Na+ channels in anesthetic effects. Methods Synaptosomes from adult rat cerebral cortex were used to determine the effects of halothane on veratridine-evoked Na+ channel-dependent Na+ influx (using 22Na+), changes in intrasynaptosomal [Na+] (using ion-specific spectrofluorometry), and neurotoxin interactions with specific receptor sites of the Na+ channel (by radioligand binding). The potential physiologic and functional significance of these effects was determined by measuring the effects of halothane on veratridine-evoked Na+ channel-dependent glutamate release (using enzyme-coupled spectrofluorometry). Results Halothane inhibited veratridine-evoked 22Na+ influx (IC50 = 1.1 mM) and changes in intrasynaptosomal [Na+] (concentration for 50% inhibition [IC50] = 0.97 mM), and it specifically antagonized [3H]batrachotoxinin-A 20-alpha-benzoate binding to receptor site two of the Na+ channel (IC50 = 0.53 mM). Scatchard and kinetic analysis revealed an allosteric competitive mechanism for inhibition of toxin binding. Halothane inhibited veratridine-evoked glutamate release from synaptosomes with comparable potency (IC50 = 0.67 mM). Conclusions Halothane significantly inhibited Na+ channel-mediated Na influx, increases in intrasynaptosomal [Na+] and glutamate release, and competed with neurotoxin binding to site two of the Na+ channel in synaptosomes at concentrations within its clinical range (minimum alveolar concentration, 1-2). These findings support a role for presynaptic Na+ channels as a molecular target for general anesthetic effects.

scholarly journals Taehwa Research Forest: A receptor site for severe pollution events in Korea during 2016

2019 ◽  
Author(s):  
John T. Sullivan ◽  
Thomas J. McGee ◽  
Ryan M. Stauffer ◽  
Anne M. Thompson ◽  
Andrew Weinheimer ◽  
...  
Keyword(s):  
Rural Communities ◽  
Eastern China ◽  
Receptor Site ◽  
The Yellow Sea ◽  
Pollution Transport ◽  
Negative Effects ◽  
Meteorological Forcing ◽  
Time Space ◽  
Receptor Sites ◽  
Pollution Events

Abstract. During the May-June 2016 International Cooperative Air Quality Field Study in Korea (KORUS-AQ), light synoptic meteorological forcing facilitated Seoul metropolitan pollution outflow to reach the remote Taehwa Research Forest (TRF) site and cause regulatory exceedances on 24 days. Two of these severe pollution events are thoroughly examined. The first, occurring on 17 May 2016, tracks transboundary pollution transport exiting eastern China and the Yello Sea, traversing the Seoul Metropolitan Area (SMA), and then reaching TRF in the afternoon hours with severely polluted conditions. This case study indicates that although outflow from China and the Yellow Sea were elevated with respect to chemically unperturbed conditions, the regulatory exceedance at TRF was directly linked in time, space, and altitude to urban Seoul emissions. The second case studied, occurring on 09 June 2016, reveals that increased levels of biogenic emissions, in combination with amplified urban emissions, were associated with severe levels of pollutions and a regulatory exceedance at TRF. The case studies are assessed with multiple aircraft, model (photochemical and meteorological) simulations, in-situ chemical sampling, and extensive ground-based profiling at TRF. These observations clearly identify TRF and the surrounding rural communities as receptor sites for severe pollution events associated with Seoul outflow, which will result in long-term negative effects to both human health and agriculture in the affected areas.

scholarly journals Structural Elements and Neuropharmacological Features Involved in the Insecticidal Properties of an Alpha Scorpion Neurotoxin: A Multidisciplinary Approach

1995 ◽  
Author(s):  
Michael Gurevitz ◽  
Michael E. Adams ◽  
Boaz Shaanan
Keyword(s):  
Plant Protection ◽  
Synergistic Effects ◽  
Insect Pest ◽  
Crop Protection ◽  
Receptor Site ◽  
Great Promise ◽  
Future Design ◽  
Receptor Sites ◽  
Insecticidal Toxins ◽  
Major Interest

Integrated pest management in modern crop protection requires the use of chemical or biological insecticides in many instances. Nontheless, the use non-selective chemical insecticides poses risks to the environment and livestock and consequently urgent need exists for safer alternatives, which target insects more specifically. Scorpions produce anti-insect selective polypeptide toxins that are biodegradable and not toxic to wam-blooded animals. Therefore, mobilization of these substances into insect pest targets is of major interest. Moreover, clarification of the molecular basis of this selectivity may provide valuable information pertinent to their receptor sites and to the future design of peptidomimetic anti-insect specific substances. These toxins may also be important for reducing the current overuse of chamical insecticides provided they have a synergistic effect with conventional pesticides. All of these objectives were addressed in this research. A direct approach for plant protection was the mobilization of toxins into target pests using baculoviral vectors. The other approach was to develop a suitable system enabling the elucidation of the toxin bioactive site, which would enable design of insecticidal peptidomimetics. In parallel, the mode of action and synergistic effects of scorpion insecticidal toxins, were studied at the sodium channel receptor site. All the above approaches show great promise and clearly indicate that scorpion insecticidal toxins may provide powerful means in insect pest control.

scholarly journals Reconstitutional mutagenesis of the maize P gene by short-range Ac transpositions.

Genetics ◽  
1992 ◽  
Vol 131 (4) ◽  
pp. 939-956 ◽  
Author(s):  
M A Moreno ◽  
J Chen ◽  
I Greenblatt ◽  
S L Dellaporta
Keyword(s):  
Insertional Mutagenesis ◽  
Chromosomal Region ◽  
Molecular Mapping ◽  
Sequence Data ◽  
Donor Site ◽  
Induced Mutations ◽  
Sequence Analyses ◽  
P Gene ◽  
Target Sites ◽  
Ac Transposition

Abstract The tendency for Ac to transpose over short intervals has been utilized to develop insertional mutagenesis and fine structure genetic mapping strategies in maize. We recovered excisions of Ac from the P gene and insertions into nearby chromosomal sites. These closely linked Ac elements reinserted into the P gene, reconstituting over 250 unstable variegated alleles. Reconstituted alleles condition a variety of variegation patterns that reflect the position and orientation of Ac within the P gene. Molecular mapping and DNA sequence analyses have shown that reinsertion sites are dispersed throughout a 12.3-kb chromosomal region in the promoter, exons and introns of the P gene, but in some regions insertions sites were clustered in a nonrandom fashion. Transposition profiles and target site sequence data obtained from these studies have revealed several features of Ac transposition including its preference for certain target sites. These results clearly demonstrate the tendency of Ac to transpose to nearby sites in both proximal and distal directions from the donor site. With minor modifications, reconstitutional mutagenesis should be applicable to many Ac-induced mutations in maize and in other plant species and can possibly be extended to other eukaryotic transposon systems as well.

Sign in / Sign up

Export Citation Format

Share Document