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Results for “LACHESINE”

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PubMed1993

Lachesin: an immunoglobulin superfamily protein whose expression correlates with neurogenesis in grasshopper embryos.

We describe the developmental expression in grasshopper (Schistocerca americana) and molecular characterization in grasshopper and fruit fly (Drosophila melanogaster) of Lachesin, a novel immunoglobulin superfamily protein. Lachesin is expressed on the surfaces of differentiating neuronal cells from the onset of neurogenesis in both the central and peripheral nervous systems. Lachesin expression begins in some cells of the neurogenic ectoderm immediately after engrailed expression begins in the posterior cells of each future segment. All neurogenic cells express Lachesin early, but only those cells that become neuroblasts continue to express Lachesin. Ectodermal cells in the neurogenic region that adopt non-neuronal fates lose Lachesin at the time that they diverge from a potentially neurogenic pathway. Neuroblasts, ganglion mother cells and neurons all express Lachesin early in their lives, but expression becomes restricted to a subset of neurons as development progresses. Sensory neurons express Lachesin as they delaminate from the body wall ectoderm. Lachesin is also present on growing axons of the CNS and PNS and becomes restricted to a subset of axons later in development. This expression is unique among known insect neurogenic genes and suggests a role for Lachesin in early neuronal differentiation and axon outgrowth. Grasshopper Lachesin is a 38 x 10(3) M(r) protein linked to cell membranes through a glycosyl phosphatidylinositol anchor. We have cloned the Lachesin gene from both grasshopper and fly. The proteins are highly conserved (70% identical) between the two species. Lachesin is similar to Drosophila amalgam, bovine OBCAM and the human poliovirus receptor, putting it into a subgroup of the immunoglobulin superfamily containing one V- and two C2-type immunoglobulin domains. Lachesin is also similar to several other vertebrate immunoglobulin superfamily proteins (TAG-1, F11, L1 and NgCAM) known to function in neurite outgrowth and other cell surface recognition events.

Amino Acid Sequence↗

PubMed2006

The IgLON protein Lachesin is required for the blood-brain barrier in Drosophila.

In the mammalian peripheral nervous system, nerve insulation depends on the integrity of paranodal junctions between axons and their ensheathing glia. Ultrastructurally, these junctions are similar to the septate junctions (SJ) of invertebrates. In Drosophila, SJ are found in epithelia and in the glia that form the blood-brain barrier (BBB). Drosophila NeurexinIV and Gliotactin, two components of SJ, play an important role in nerve ensheathment and insulation. Here, we report that Drosophila Lachesin (Lac), another SJ component, is also required for a functional BBB. In the developing nervous system, Lac is expressed in a dynamic pattern by surface glia and a subset of neurons. Ultrastructural analysis of Lac mutant embryos shows poorly developed SJ in surface glia and epithelia where Lac is expressed. Mutant embryos undergo a phase of hyperactivity, with unpatterned muscle contractions, and subsequently become paralyzed and fail to hatch. We propose that this phenotype reflects a failure in BBB function.

Animals↗

PubMed1973

Interaction of benzilylcholine mustard, benzilylcholine and lachesine with the histamine receptor in the longitudinal muscle of guinea-pig ileum.

1. The histamine receptors of longitudinal muscle strips from guinea-pig ileum were inactivated on extended exposure to concentrations of benzilylcholine mustard (BCM) above 10(-6)M. These concentrations are 3 orders of magnitude greater than those required for inactivation of the muscarinic receptors. Mepyramine (3 x 10(-8)M) afforded complete protection for the histamine receptor against the effects of BCM.2. Recovery from block at 30 degrees C was very slow with a first-order rate constant of approximately 10(-7) s(-1).3. The rate constant, k(2), for the alkylation reaction in which the reversible BCM-receptor complex is converted into an irreversible complex is much greater than the rate constant, k(-1), for dissociation of the reversible complex. The value of the rate constant, k(1), for formation of the reversible complex was 1.1 +/- 0.2 x 10(3)M(-1) s(-1).4. These observations suggested that k(1) was probably not much greater than for BCM acting on the muscarinic receptor, even though the value of k(1) was reduced by more than 2 orders of magnitude. This effect has been established for benzilylcholine and lachesine, reversible analogues of BCM. For both drugs k(1) for the histamine receptor was approximately 3 orders of magnitude less than for the muscarinic receptor, whereas k(1) was greater by a factor of only 6.

Acetylcholine↗

PubMed2004

Lachesin is a component of a septate junction-based mechanism that controls tube size and epithelial integrity in the Drosophila tracheal system.

Organ morphogenesis requires the coordinated activity of many mechanisms involved in cell rearrangements, size control, cell proliferation and organ integrity. Here we report that Lachesin (Lac), a cell surface protein, is required for the proper morphogenesis of the Drosophila tracheal system. Homozygous embryos for Lac mutations, which we find fail to complement the previous identified bulbous (bulb) mutation, display convoluted tracheal tubes and tube breaks. At the cellular level, we can detect enlarged cells, suggesting that Lac regulates organ size by influencing cell length rather than cell number, and cell detachments, indicating a role for Lac in cell adhesion. Results from an in vitro assay further support that Lac behaves as a homophilic cell adhesion molecule. Lac co-localizes with Septate Junction (SJ) proteins, and ultrastructural analysis confirms that it accumulates specifically at this type of cellular junction. In Lac mutant embryos, previously characterized components of the SJs are mislocalized, indicating that the proper organization of SJs requires Lac function. In addition, mutations in genes encoding other components of the SJs produce a similar tracheal phenotype. These results point out a new role of the SJs in morphogenesis regulating cell adhesion and cell size.

Animals↗

PubMed1951

E-3--Lachesine.

Explore the source record for details and available documents.

Cataract Extraction↗

PubMed1964

STIMULANT ACTIONS OF VOLATILE ANAESTHETICS ON SMOOTH MUSCLE.

A number of volatile anaesthetics, and some compounds synthesized in the search for new anaesthetics, have been tested on guinea-pig intestinal smooth muscle in vitro. All the compounds produced a contractile response. This effect did not correlate well with convulsant activity in vivo among the compounds tested. Two kinds of stimulant effect were distinguishable: (1) Rapid, transient contractions, abolished by cocaine or lachesine; most of the anaesthetics in clinical use had this action. (2) Slow, sustained contractions, unaffected by cocaine or lachesine; this effect predominated among the fluorinated ring compounds. Hexamethonium and mepyramine did not affect the contractile response to any of the compounds. The first type of effect presumably represents excitation of postganglionic nerve cells, while the second type is a direct action on the muscle cell. The action of perfluorobenzene, which is of the latter kind, was studied further. Adrenaline and lack of calcium diminished the contraction in parallel with the contraction to histamine, which suggests that the cell membrane was the site of action; in contrast to the stimulant action of histamine or acetylcholine, the effect was highly temperature-sensitive, being almost abolished by cooling to 32 degrees C, and enhanced at 40 degrees C. The depressant action of anaesthetics on smooth muscle is affected very little by temperature changes. These findings are discussed in relation to other observations which suggest a stimulant action of volatile anaesthetics on excitable tissues. Protein denaturation is tentatively suggested as a mechanism of action.

Acetylcholine↗

PubMed1980

Muscarinic receptors in rat sympathetic ganglia.

1 Potential changes in isolated superior cervical ganglia of the rat produced by muscarinic-receptor agonists were recorded by an extracellular ;air-gap' method.2 Muscarinic agonists produced a delayed low-amplitude ganglion depolarization, frequently preceded by a hyperpolarization. Potentials were enhanced by reducing [K(+)](o) or [Ca(2+)](o).3 Mean ED(50) values (muM) for depolarization at 25 degrees C were: oxotremorine 0.004, methylfurmethide 0.11, (+/-)-muscarine 0.24, furmethide 1.56, pilocarpine 4.81 and AHR-602 (N-benzylpyrrolidylacetate methobromide) 10.8. Responses produced by oxotremorine, pilocarpine and AHR-602 showed some characteristics of ;partial agonism'. ED(50) values (muM) for choline esters (measured in the presence of 2.5 mM hexamethonium) were: acetylcholine 3.2, methacholine 59 and bethanechol 78.4 Responses to muscarine were antagonized by hyoscine (K(I) 0.49 nM) atropine (K(I) 0.24 nM) methylscopolamine (K(I) 0.09 nM) lachesine (K(I) 0.15 nM) and (weakly) by hexamethonium (K(I) 0.2 mM). Propylbenzilylcholine mustard produced irreversible antagonism with an apparent onset rate constant of 2 x 10(5) M(-1)S(-1).5 Depolarization was accompanied by facilitation of submaximal ganglionic transmission.6 Muscarine (1 to 100 muM) initially reduced, then increased, the rate of (86)Rb(+)-efflux from isolated ganglia at both 6 and 120 mM [K(+)](o). These effects were reduced by 1 muM hyoscine.7 No consistent change in the amounts of cyclic 3',5'-guanosine monophosphate in isolated ganglia accompanying muscarinic depolarization could be detected.8 Mean against ED(50) values (muM) for contracting the rat isolated ileum were: oxotremorine 0.012, methylfurmethide 0.29, (+/-)-muscarine 0.48, pilocarpine 7.8 and AHR-602 9.9. Mean antagonist K(I) values (nM) were: hyoscine 0.17, atropine 0.34 and lachesine 0.27.9 It is concluded that ganglionic muscarinic receptors are quite similar to ileal receptors in terms of agonist ED(50) and antagonist K(I) values, and that the major difference between them lies in the greater ;efficacy' of certain agonists (pilocarpine, AHR-602 and McN-A-343) on the ganglion.

Animals↗

PubMed2001

Embryonic development of the central projection of auditory afferents (Schistocerca gregaria, Orthoptera, Insecta).

The auditory system of Schistocerca gregaria is a well investigated sensory network in the adult grasshopper. Here we present a first study on the embryonic development of this neuronal network. Focussing on the auditory receptor cells we show that they differentiate axonal processes at around 45% of embryonic development. These axons fasciculate with the intersegmental nerve and enter the central nervous system by 45-50% of development. First collaterals sprout into the major arborization area, the frontal auditory projection area of the metathoracic ganglion by 60%. This projection increases in density until an adult-like morphology is established by 90% of development. Furthermore, by the end of embryogenesis all three types of receptor fiber projections can be distinguished. This development is independent of a hearing ability, which develops much later during postembryonic life. The auditory projection co-develops with the fusion of neuromeres to the metathoracic ganglion, the formation of the target neuropile areas and the expression of the synapse associated molecule synapsin. Fasciclin I and Lachesin, both potential axon-guidance molecules, are expressed strongly on both, peripheral and central auditory pathways and, although much weaker, within the synaptic target area.

Animals↗

PubMed1995

Requirement of RNA synthesis for pathfinding by growing axons.

The effects of actinomycin D were studied in cultured grasshopper embryos at different stages of development by following the outgrowth patterns of identified neurones known as aCC, pCC, and Q1. When administered at stages occurring before 31% of embryonic development, actinomycin D (0.05-0.10 microM for 24-48 hours) prevented axon extension, whereas it did not affect the development of the nervous system in embryos older than 34% of development. At 31-34% of development, actinomycin D perturbed pathfinding of aCC without blocking axon extension. Thus, only 22% of the aCCs (n = 271) in embryos treated with actinomycin D extended an axon along the intersegmental nerve as in control embryos. In the remaining embryos, aCC failed to turn into the intersegmental nerve root; its growth cone remained in the longitudinal connective, above or below the turning point. Neurones of the group caudal to the intersegmental nerve root could extend along either the anterior or posterior commissure of the next posterior segment. In contrast to the observations made with aCC, only 1.2% of pCC (n = 166) and 0.0% of Q1 (n = 45) in embryos treated with actinomycin D showed axon growth along aberrant pathways. The position of the growth cones of most pCCs and all Q1s observed were in various points along their normal pathway. Both pCC and Q1, as a population, showed an extension rate significantly lower than that of their control counterparts. The effect of actinomycin D on aCC pathway choice was probably mediated by inhibition of RNA synthesis, because incorporation of uridine into RNA was reduced by 40%. The labelling of several monoclonal antibodies (1C10, 3B11, 7F7) that recognise surface glycoproteins (lachesin, fasciclin I, and REGA-1) involved in nervous system development of grasshopper embryos was suppressed. Our results suggest that the navigation of some axons along different pathways requires the synthesis of new mRNA.

Animals↗

PubMed1980

Antimuscarinic agents: furan analogs of benzilate esters.

The methiodide and ethiodide salts of 5-(dimethylaminomethyl)- and 5-(diethylaminomethyl)-alpha, alpha-diphenylfurfuryl alcohol were prepared, These compounds may be considered as furan analogs of dialkylaminoethyl benzilate alkiodides. The pA2 values of these compounds as antagonists of acetylcholine were determined on rat jejunum preparation. All four compounds were significantly less potent than the analogous ester antimuscarinic lachesine. The furan ring cannot be substituted for the ester moiety of typical antimuscarinics. Possible modes of binding by antagonists to the receptor proposed previously are considered that might account for this less-than-expected antimuscarinic activity.

Animals↗

PubMed1963

SOME EFFECTS OF ATROPINE ON SMOOTH MUSCLE.

Contractions of the nerve-free smooth muscle of the chick amnion, either spontaneous or in response to electrical or mechanical stimuli, are potentiated by high conentrations (10(-5) g/ml.) of atropine sulphate. In addition hyoscine, homatropine, lachesine, propantheline bromide and atropine N-methyl and atropine N-butyl salts potentiate spontaneous activity in the amnion. The effects of atropine do not appear to depend on inhibition of cholinesterase; on labilization, stabilization or depolarization of the muscle cell membrane; or on an increase in metabolism. It is suggested that the effects are the result of blockade of the muscarinic acetylcholine receptors. The way in which this may facilitate the conducted response is discussed.

Amnion↗

PubMed1981

A re-evaluation of acetylcholine receptors on feline Renshaw cells.

1 The effects of atropine, methylatropine and lachesine administered by ionophoresis were examined on responses of Renshaw cells to acetylcholine, acetyl-beta-methylcholine, nicotine and DL-muscarine in cats anaesthetized with pentobarbitone or chloralose. 2 The antagonists were as effective in antagonizing excitation by nicotine as they were in antagonizing excitation by acetylcholine and were only slightly more effective in antagonizing excitation by acetyl-beta-methylcholine. 3 These results are discussed in relation to the characterization of acetylcholine receptors on Renshaw cells. 4 It is concluded that there are two distinct populations of receptors but that the nicotinic receptors are non-selective in their activation by agonists and antagonists, whereas the muscarinic receptors display greater selectivity.

Acetylcholine↗

PubMed1976

Aggregation of antiacetylcholine drugs in aqueous solution: micellar properties of some diphenylmethane derivatives.

Light scattering methods have been used to examine the aggregation in aqueous solution of a series of antiacetylcholine drugs based on the diphenylmethane nucleus. The drugs investigated included adiphenine hydrochloride, piperidolate hydrochloride, benztropine mesylate, orphenadrine hydrochloride, chlorphenoxamine hydrochloride, lachesine hydrochloride, poldine methylsulphate, pipenzolate bromide, clidinium bromide, benzilonium bromide and ambutonium bromide. A micellar pattern of association was established for all compounds and critical micellar concentrations and aggregation numbers have been determined.

Acetylcholine↗

PubMed2026

Adaptation to Plant Defence in an Agricultural Insect Pest: Integrating Genome Scans and Gene Expression in the Soybean Aphid Reveals Multi-Genic Pathways.

In agroecosystems, intense selection pressures cause species to adapt and spread, often leading to the evolution and persistence of pests. Understanding how pests rapidly adapt can help develop sustainable strategies for their management and improve agroecosystem health. Pest adaptation involves stable variations in DNA sequence, as well as dynamic shifts in gene expression, often mediated by non-coding regulatory elements. We examined adaptation to plant defences in the soybean aphid, Aphis glycines, in which virulent aphids have overcome plant defences and avirulent aphids have not. Previous data with laboratory colonies suggested that virulent aphids have higher overall gene expression, including transposable elements, some of which influence gene regulation. However, we lack information on how genetic variation in natural populations impacts adaptation and potentially gene regulation. We integrated population genome scans of field-collected, soybean aphid populations with gene expression profiles of virulent and avirulent laboratory colonies to uncover connections between genetic differentiation and gene regulation for virulence. Genome scan methods found 2144 single nucleotide polymorphisms (SNPs) with significant genetic differentiation (i.e., outliers) in field-collected populations. These SNPs were near 1004 genes, representing 5.16% of the effective number of genes. Based on previous RNA-Seq data with laboratory colonies, we found 3160 genes and 147 long non-coding RNAs (lncRNAs) with differential expression among virulent and avirulent biotypes. By integrating both data sets, we identified 16 genes and 5 long non-coding RNAs with differential expression and that were associated with an outlier SNP (within 10 kbp). We validated SNPs with additional field collected aphids and found an aphid clone with stronger virulence than our laboratory virulent colony, surviving on 2 different aphid-resistant soybean varieties. This new virulent clone had fixed allele differences at 9 SNPs compared to our avirulent and other virulent colony. Field collected soybean aphids matching the phenotype of this new virulent clone had significant genetic differentiation with 3 outlier SNPs near genes related to zinc transport and lachesin compared to field collected avirulent aphids. Our entire data reinforced the importance of a potential multi-genetic response to overcome plant defence and generates new insights into complex genetic and regulatory mechanisms involved in insect-plant interactions.

Animals↗

PubMedDate not supplied

[Role of the central and peripheral cholinoreceptors in the processes of short-term memory].

Short-term memory with blocked cholinoreceptors was studied by the method of deferred reactions in the choice of one of 3--4 feeding troughs in tests staged on 5 dogs and 5 cats. Disturbances of short-term memory were caused by blocking of central m-cholinoreceptors with benactizyne (0.1--0.4 mg/kg). On abolishing peripheral symptoms arising under the effect of chlorpromazine with carbocholine (0.001 mg/kg) the short-term memory disturbances go on persisting. Blocking of peripheral m-cholino-receptors with lachesine (0.01--0.1 mg/kg) does not have any significant effect on the short-term memory. Under the blocking action of pediphen (0.5--2 mg/kg) on the cerebral n-cholinoreceptors the short-term memory improves with reduced memorization capacity.

Animals↗