Innervation of the urinary bladder of Ovis aries L

The authors have extended a preliminary study about the innervation of urinary bladder, confirming the previous results pointing out the presence of metasympathetic ganglions in the wall of urinary bladder. Therefore nine urinary bladders of Ovis aries of different age and both sexes have been studied by Ruffini, Bodian and Bielschowsky's staining methods. It's possible summarize the data on the innervation of urinary bladder in the following way: in the tunica adventitia there are motor and sensitive bundles of myelinated nervous fiber. The formers, after many divisions, penetrate into the tunica muscularis contacting bundles of smooth muscle fibers, while the latters after several divisions after giving rise to thinner bundles, produce Pacini-like and Ruffini-like sense corpuscles and free nervous terminations. Furthermore, some metasympathetic ganglions of different size have been detected throughout the running of the bundles. In the tunica submucosa a diffuse and peculiar non myelinated network is observed, arising from the vegetative nervous fibers.     

Guanine nucleotides inhibit binding of agonists and antagonists to soluble opiate receptors

The guanine nucleotides GDP, GTP, and guanosine-5'-(beta, gamma-imido)triphosphate inhibit binding of opiates and opioid peptides to receptors solubilized from membranes of neuroblastoma X glioma NG108-15 hybrid cells. The inhibition reflects decreased affinity of receptors for opioid ligands. Whereas in membranes, only opioid agonist binding is sensitive to guanine nucleotide inhibition, both agonist and antagonist binding is reduced in the case of soluble receptors. Furthermore, soluble receptors are more sensitive to the effects of guanine nucleotides than are membrane-bound receptors. These observations are consistent with the suggestion that solubilized receptors may be complexes of an opiate binding protein and a guanine nucleotide-sensitive regulatory component.     

The photoreceptor localization confirms the spectral heterogeneity of ommatidia in the male small white butterfly,<Emphasis Type="Italic"> Pieris rapae crucivora</Emphasis>

The compound eye of Pieris rapae crucivora contains ventrally three types of histologically distinct ommatidia. An ommatidium contains nine photoreceptors, four of which (R1-4) construct the distal tier of the rhabdom. We determined the sensitivity spectra of the R1-4 distal photoreceptors in each type of ommatidia by intracellular electrophysiology and identified UV, blue, double-peaked blue, green, and a green receptor with depressed sensitivity in the violet. We localized these receptors in each type of ommatidia by injecting dye after the recording. In type I ommatidia the R1 and R2 cells are UV and blue receptors. When R1 is UV sensitive, R2 is always blue sensitive, or vice versa. R3 and R4 in type I are both green receptors. In type II, R1 and R2 are both double-peaked blue receptors and R3 and R4 are both green receptors with depressed sensitivity in the violet. In type III, R1 and R2 are both UV, and R3 and R4 are green receptors. The double-peaked blue, and green receptors with depressed sensitivity in the violet in type II ommatidia have depressed sensitivity at 420 nm, which is probably due to the filtering effect of a fluorescing material present in the type II ommatidia. Spectral heterogeneity of ommatidia seems to be a common design of insect compound eyes.     

Some models of the evolution of altruistic behaviour between siblings

When a fluid membrane, containing mobile receptors for some ligand, is placed in a diffusion gradient of that ligand, the receptors will redistribute to become more concentrated in those regions of the membrane which are associated with the higher concentrations of ligand. The thermodynamics of this effect are developed. The significance of this effect as a possible step in the transduction of the orientational information content of a diffusion gradient to a cell is discussed. It is pointed out that fluid membrane receptors should potentially be more sensitive transducers of the orientational information content of the gradient than would fixed membrane receptors, and that the transduction sensitivity will rise as the number of ligand binding sites per receptor rises.     

Four residues of the extracellular N-terminal domain of the NR2A subunit control high-affinity Zn2+ binding to NMDA receptors

NMDA receptors are allosterically inhibited by Zn2+ ions in a voltage-independent manner. The apparent affinity for Zn2+ of the heteromeric NMDA receptors is determined by the subtype of NR2 subunit expressed, with NR2A-containing receptors being the most sensitive (IC50, approximately 20 nM) and NR2C-containing receptors being the least sensitive (IC50, approximately 30 microM). Using chimeras constructed from these two NR2 subtypes, we show that the N-terminal LIVBP-like domain of the NR2A subunit controls the high-affinity Zn2+ inhibition. Mutations at four residues in this domain markedly reduce Zn2+ affinity (by up to >500-fold) without affecting either receptor activation by glutamate and glycine or inhibition by extracellular protons and Ni2+ ions, indicating that these residues most likely participate in high-affinity Zn2+ binding.     

Features of the receptors of the alar system of locusts which have lost their ability to fly

Using two species of locusts, Romalia microptera Beavy and Podisma pedestris L., receptors of the wing apparatus are described: campaniform sensillas of the wing, hair receptors of the tegula, chordotonal organ and thorax stretch receptor. A comparative analysis of the receptors mentioned with the homologous sensitive organs, participating in the control of wing movements, is performed in well flying species (Locusta migratoria migratorioides and Schistocerca gregaria). Loss of ability to fly is accompanied with a sharp decrease in the wing campaniform sensillas and in the tegula proprioceptive hairs. Simultaneously, there is loss of connection between the thorax receptors and the wing elements that are present in good flyers. The thorax stretch receptor begins to innervate the longitudinal dorsal muscle, as it is observed in the abdominal segments. The data obtained make it possible to speak about homology of the tergal chordotonal organs and the thorax and abdomen stretch receptors and about the pathways of their evolution, when the insects obtain and loose their ability to fly.     

Comparison of male and female olfactory cell response to pheromone compounds and plant volatiles in the turnip moth, Agrotis segetum

ABSTRACT. Pheromone and plant volatile perception was studied with electroantennogram and single sensillum techniques in male and female turnip moths, Agrotis segetum Schiff. Lepidoptera, Noctuidae. The female is insensitive to the pheromone components and her receptors are specialized for plant volatile reception. The specific pheromone receptors on the male antenna are also sensitive to plant volatiles. The male was in addition found to have specialized plant volatile receptors. The biological significance of the different response profiles in males and females, and a possible hypothesis for the evolutionary specialization of olfactory receptors are discussed.     

Analogues of Somatostatin Bind Selectively to Brain Somatostatin Receptor Subtypes

Somatostatin (SRIF) is a neurotransmitter that produces its multiple effects in the CNS through interactions with membrane-bound receptors. Subtypes of SRIF receptors are found in the CNS that are distinguished by their sensitivities to the cyclic hexapeptide MK-678, such that SRIF1 receptors are sensitive to MK-678 and SRIF2 receptors are insensitive to MK-678. In the present study, we further examined the selectivities of a series of structurally diverse SRIF analogues for SRIF receptor subtypes. SRIF receptors were labeled by 125I-Tyr11-SRIF, which has indistinguishable affinities for SRIF receptor subtypes. The inhibition by MK-678 was incomplete, indicating this peptide is highly selective for a subtype of SRIF receptor that we have termed the SRIF1 receptor. The binding of 125I-MK-678 to SRIF1 receptors was monophasically inhibited by SRIF, the octapeptides (such as SMS-201-995), and the hexapeptides (such as MK-678), consistent with the highly selective labeling of a subtype of SRIF receptor. In contrast, the smaller CGP-23996-like analogues did not inhibit 125I-MK-678 binding to SRIF1 receptors. The binding of 125I-CGP-23996 to SRIF receptors was inhibited by SRIF and the octapeptides with Hill coefficients of less than 1, indicating that 125I-CGP-23996 labels multiple SRIF receptor subtypes. The hexapeptides and CGP-23996-like compounds produced only partial inhibitions of 125I-CGP-23996 binding, which were additive, indicating selective interactions of these compounds with the different receptor subpopulations labeled by 125I-CGP-23996. 125I-Tyr11-SRIF binding and 125I-CGP-23996 binding to SRIF receptors were likewise only partially affected by 100 microM guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), a concentration that completely abolishes specific 125I-MK-678 binding to SRIF1 receptors. The component of 125I-CGP-23996 labeling that was sensitive to GTP gamma S was also MK-678 sensitive. Thus, two subpopulations of SRIF receptors exist in the CNS. The SRIF1 receptor is sensitive to cyclic hexapeptides such as MK-678 and to GTP gamma S but insensitive to smaller CGP-23996-like compounds. The SRIF2 receptor is sensitive to the CGP-23996-like compounds and can be selectively labeled by 125I-CGP-23996 in the presence of high concentrations of the hexapeptides or GTP gamma S because, unlike the SRIF1 receptor, the SRIF2 receptor is insensitive to these agents. The SRIF receptor subtype-selective peptide analogues will be useful in the future characterization of the functions mediated by SRIF receptor subtypes in the CNS.     

Processing of vibratory and acoustic signals by ventral cord neurones in the cricket Gryllus campestris

The responses of single vibratory receptors and ascending ventral cord interneurones were studied extracellularly in Gryllus campestris L. The physiology of the vibration receptors resembled those found in tettigoniids and locusts. The frequency responses of the subgenual receptors provide two possible cues for central frequency discrimination: differences in mean tuning between groups of receptors in the different leg pairs and a range of receptors tuned to different frequencies within one subgenual organ.Most of the ascending vibratory interneurones were highly sensitive in either the low or high frequency range. Broadbanded neurones were less sensitive. The characteristic sensitivity peaks of these units are due mainly to receptor inputs from a particular leg pair, although most central neurones receive inputs from all 6 legs. Only one neurone type, TN1 received excitatory inputs from both auditory and vibratory receptors; its responses were greatly enhanced by the simultaneous presentation of both stimulus modes. The responses to sound stimuli of AN2, on the other hand, were inhibited by vibration. No other auditory interneurones investigated were influenced by inputs from vibration receptors. Central processing of vibratory information in the cricket is compared with that of tettigoniids and locusts.     

The Effects of Neuraminidase and Gangliosides on Ovarian LH/hCG Receptors During Rat Development

Ovaries of neonatal rats are not endowed with specific LH/hCG receptors up to 6–8 days of age. Treatment of ovarian membranes of the neonatal rat with neuraminidase results in a specific binding of radioactively labeled hCG, while an increase of hormone binding is observed after neuraminidase treatment of ovarian membranes of the 21-day-old rat. These changes in hormone receptor sites in the ovary are dependent on the neuraminidase concentration used and are due to a receptor with a dissociation constant (K_D) of about 10⁻⁹ M. The K_D of the receptor in the LH/hCG sensitive ovary without neuraminidase treatment is about 10⁻¹⁰ M. These results indicate the presence of two different LH/hCG receptors in the ovarian membrane. The unmasking effect of neuraminidase onto LH/hCG receptors indicate that ganglioside-like structures are responsible for the masking of receptors in the neonatal, insensitive rat ovary and also in the 21-day-old sensitive ovary. Ganglioside preparations are able to inhibit the binding, and the fractionation of ovary gangliosides results in a fraction with a rather high inhibition potency of LH/hCG binding to the receptor. It is hypothesized that the masked receptors in the sensitive period represent a store of receptors for the reconstitution of the ovarian cells with active receptors after internalization of the hormone-receptor complex. Thus the masking of the receptors in the early postnatal rat ovary could be a prerequisite for the female differentiation of hypothalamic centers. The observed neuraminidase effect in vitro could reflect a physiologic situation. Neuraminidase was found in the ovary, and during early postnatal development the neuraminidase activity pattern coincides with that of the ovarian LH/hCG receptor changes.     

A green-fluorescent-protein-based assay for the characterization of G-protein-coupled receptors

A simple and sensitive system to monitor activation and pharmacology of G-protein-coupled receptors in mammalian cells is described. It is based on cAMP-responsible-element-regulated expression of green fluorescent protein (GFP). Cotransfection with appropriate G-protein-coupled receptors and subsequent activation with agonists induces expression of GFP in a dose-dependent manner. This system is suited for the analysis of most G-protein-coupled receptors, including those that are coupled to Gs, Gi, and Gq. It can replace reporter systems for G-protein-coupled receptors currently in use. Time-consuming and labor-intensive analysis is avoided because it is a noninvasive system, which allows multiple reprobing without disturbing the cells. In addition, adaptation to high-throughput approaches is possible. Together with human embryonic kidney cells, it is a zero-background expression system, making it ideally suited to the pharmacological characterization of cloned receptors, to expression cloning experiments, and to the identification of the natural ligand of orphan G-protein-coupled receptors.     

Sensory interneurons: some observations concerning the physiology and related structural significance of two cells in the crayfish brain

Two large interneurons in the crayfish brain which are sensitive to vibrational stimuli were injected with the fluorescent dye Procion Yellow. The dendritic branching profiles reflect the directional sensitivity of their respective mechanoreceptive fields on the cephalic appendages and integument. One interneuron branches exclusively on the contralateral side of the brain and receives monosynaptic input from the contralateral antenna; the second interneuron branches primarily on the ipsilateral side and is more sensitive to input from ipsilateral receptors although its receptive field is bilateral. The data suggest that these cells are primary and secondary sensory interneurons, respectively.     

Phage receptors of Escherichia coli. Basic components of the outer membrane of E. coli as phage receptors

Major outer membrane components which determine the structure and the barrier function of membrane Gram-negative bacteria are receptors for many bacteriophages. LPS--the major component of the outer membrane of Enterobacteria can be used by some phages with wide host range specificity. The other component of the outer membrane frequently include phage receptor component is OmpA protein. OmpA protein different areas can be used as receptors for different phages T--even group. A large group of phage receptors compose porin proteins, which are discovered in 32 species of bacteria. The synthesis of major porin proteins, which a receptor for several phages, are regulated by sufficiently complex system of some genes. These genes are sensitive to the changes of environment.     

The effects of neuraminidase and gangliosides on ovarian LH/hCG receptors during rat development

Ovaries of neonatal rats are not endowed with specific LH/hCG receptors up to 6-8 days of age. Treatment of ovarian membranes of the neonatal rat with neuraminidase results in a specific binding of radioactively labeled hCG, while an increase of hormone binding is observed after neuraminidase treatment of ovarian membranes of the 21-day-old rat. These changes in hormone receptor sites in the ovary are dependent on the neuraminidase concentration used and are due to a receptor with a dissociation constant (KD) of about 10(-9) M. The KD of the receptor in the LH/hCG sensitive ovary without neuraminidase treatment is about 10(-10) M. These results indicate the presence of two different LH/hCG receptors in the ovarian membrane. The unmasking effect of neuraminidase onto LH/hCG receptors indicate that ganglioside-like structures are responsible for the masking of receptors in the neonatal, insensitive rat ovary and also in the 21-day-old sensitive ovary. Ganglioside preparations are able to inhibit the binding, and the fractionation of ovary gangliosides results in a fraction with a rather high inhibition potency of LH/hCG binding to the receptor. It is hypothesized that the masked receptor in the sensitive period represent a store of receptors for the reconstitution of the ovarian cells with active receptors after internalization of the hormone-receptor complex. Thus the masking of the receptors in the early postnatal rat ovary could be a prerequisite for the female differentiation of hypothalamic centers. The observed neuraminidase effect in vitro could reflect a physiologic situation. Neuraminidase was found in the ovary, and during early postnatal development the neuraminidase activity pattern coincides with that of the ovarian LH/hCG receptor changes.     

Insights into the activation mechanism of the visual receptor rhodopsin

Recent advances in the structural biology of GPCRs (G-protein-coupled receptors) have provided insights into their structure and function. Comparisons of the visual and ligand-activated receptors highlight the unique elements of rhodopsin that allow it to function as a highly sensitive dim-light photoreceptor in vertebrates, as well as the common elements that it shares with the large class A GPCR family. However, despite progress, a number of questions remain unanswered about how these receptors are activated.     

The capping of receptors for the epidermal growth factor and the participation of the cytoskeleton in this process in A-431 cells

Epidermal growth factor (EGF) receptor capping results from the interaction between the receptors and polyvalent ligands in A-431 cells examined in suspension at 22 degrees C. Colocalization of actin and spectrin with the ligand-receptor complexes during the redistribution was shown using double immunofluorescence. The obtained data show that the cortical microfilaments are involved in capping. EGF receptors become associated with the Triton-insoluble cytoskeleton as a consequence of ligand binding. EGF-receptor capping is not sensitive to the action of cytochalasin B. Capping in A-431 cells is discussed as a new model for studying the redistribution of the ligand-receptor complex.     

Neurophysiology of the vibration sense in locusts and bushcrickets: Response characteristics of single receptor units

The response characteristics of the vibration receptors in the legs of the migratory locust, Locusta migratoria, and the tettigoniid Decticus verrucivorus were investigated electro-physiologically by single cell recordings. The legs were stimulated by sinusoidal vibrations. There are four types of vibration receptor in each leg of Locusta and Decticus, which can be classified physiologically. One type—most probably campaniform sensilla—shows a phase-locked response to vibrations from 30 to 200 Hz, its threshold reflecting the displacement. A second type shows similar responses in the same frequency range, but its reactions depend on the stimulus acceleration. The receptor cells of the subgenual organ are very sensitive to vibration from 30 to at least 5000 Hz, and their responses depend on acceleration. There are two types of subgenual receptors, one of which shows a clear maximum of sensitivity between 200 and 1000 Hz, with a threshold below 0.01 m/sec^?2 acceleration. Subgenual receptors with different thresholds and different characteristic frequencies occur in each leg. The receptors of each leg pair have quite similar mean sensitivities and characteristic frequencies. However, in the front legs of tettigoniids the more sensitive subgenual receptors and an additional receptor type also respond to low-frequency airborne sound up to 10 kHz.     

Composition and histotopography of receptors in antagonist muscles of the radial area of the human forearm

The m. extensor carpi radialis longus and m. flexor carpi in newborns are richly saturated in terminal sensitive apparatuses and are presented as peculiar reflexogenic zones. Quantity and topography of receptors in these zones are similar. Nevertheless, functionally different muscle areas (both in the extensor and flexor) are not equally supplied with the receptory apparatuses.     

A high-affinity monoclonal antibody against the FLAG tag useful for G-protein-coupled receptor study

The FLAG sequence (DYKDDDDK) is an artificial sequence widely used to detect, quantify, and purify proteins expressed as FLAG-fusion proteins. Several highly specific monoclonal antibodies for FLAG are commercially available; however, they are not always sensitive enough to detect proteins expressed at low levels and can give rise to unacceptable levels of background signal when used for immunostaining in vitro and in vivo. The current study reports the successful establishment of hybridoma cells that produce an extremely high-affinity antibody to FLAG, namely 2H8 Ab. 2H8 Ab stained FLAG-tagged G-protein-coupled receptors more strongly than commercially available antibodies in both flow cytometry and immunostaining experiments with no background staining. 2H8 was sensitive enough to detect FLAG-tagged G-protein-coupled receptors and soluble proteins in crude preparations, which could not be achieved using commercially available antibodies. Only 10 ng of 2H8 Ab was required to immunoprecipitate FLAG-tagged G-protein-coupled receptors from cell lysates. Of note, 2H8 stained FLAG-tagged BLT2, a low-affinity leukotriene B4 receptor, expressed in vivo in the small intestine of mice under control of the villin promoter. Thus, 2H8 Ab is a promising tool for analyzing various FLAG-fusion proteins, particularly G-protein-coupled receptors, both in vitro and in vivo.