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M J Greenberg

Publications and source records attributed to M J Greenberg.

At least 19 recordsLinked to original sources
PubMed1994

FMRFamide-related peptides from the kidney of the snail, Helisoma trivolvis.

Three FMRFamide-related peptides (FaRPs) were purified and characterized from the kidney of the snail, Helisoma trivolvis, by HPLC and detected using two radioimmunoassays (RIA) for FaRPs. Automated sequencing and mass spectrometry of the isolated peptides suggest the following sequences: Phe-Met-Arg-Phe-NH2 (FMRFamide), Phe-Leu-Arg-Phe-NH2 (FMRFamide), and Gly-Asp-Pro-Phe-Leu-Arg-Phe-NH2 (GDPFLRFamide). The FaRPs, predominantly the heptapeptides, were also detected by HPLC and RIA in other osmoregulatory tissues such as the skin, mantle, and the hemolymph. The level of FaRPs, detected by radioimmunoassay, appears to be lower in snails kept under hyposmotic stress than in snails kept under isosmotic stress. The FaRPs appear to be involved in osmoregulation in H. trivolvis.

Amino Acid Sequence↗
PubMed1994

Characterization and solubilization of the FMRFamide receptor of squid.

The optic lobe of squid (Loligo pealei) contains FMRFamide receptors that can bind an iodinated FMRFamide analog: [125I]-desaminoTyr-Phe- norLeu-Arg-Phe-amide ([125I]-daYFnLRFa). Radioligand binding assays revealed that squid FMRFamide receptors are specific, saturable, high affinity sites (Kd = 0.15 nM) densely concentrated in optic lobe membranes (Bmax = 237 fmole/mg protein). The receptors appeared to be coupled to Gs because guanine nucleotides inhibit receptor binding and the stimulation of adenylate cyclase by FMRFamide is GTP-dependent. Both the binding and cyclase data showed that FMRFamide, but not FMRF-OH, interacts at FMRFamide receptors; thus the C-terminal Arg-Phe-amide is critical for binding. The high binding affinity of FMRFamide (0.4 nM IC50) was specific for FMRFamide-like peptides. The structure-activity relations of many FMRFamide analogs were defined in detail and were nearly identical for both the membrane-bound and detergent-solubilized receptors. We also found that squid optic lobe contains FMRFamide-like reactivity as measured with both a radioimmunoassay and a radioreceptor assay. Moreover, we have sequenced a fragment of genomic DNA that encodes a FMRFamide precursor. Our findings in sum suggest that FMRFamide is a neurotransmitter in squid optic lobe, and that this tissue is a good source from which to purify FMRFamide receptors.

Adenylyl Cyclases↗
PubMed1993

Phe-Met-Arg-Phe-NH2 (FMRFa)-related peptides inhibit Na(+)-Ca2+ exchange in cardiac sarcolemma vesicles.

The molluscan cardioexcitatory tetrapeptide FMRF-amide (Phe-Met-Arg-Phe-NH2) and related peptides inhibit Na(+)-Ca2+ exchange in calf cardiac sarcolemma vesicles. FMRFa itself has a low inhibitory potency (IC50 = 750 microM) which completely resides in its COOH-terminal RFa portion. The physiologically active analog FLRFa is 10-fold more potent (IC50 = 60 microM). Two other substitutions of the Met2 in FMRFa, by either Ile or Lys increase inhibitory potency 7- and 50-fold, respectively. The inhibitory potency increases 300-500-fold if the NH2-terminal Phe1 in FMRFa is substituted by either Val or His (IC50 = 1-2 microM). The inhibitory activity of WnLRFa (IC50 = 40 microM) is lost when either the NH2-terminal amino group is acylated or the NH2-terminal Trp1 is deleted. These data suggest that the COOH-terminal portion is essential for the basic low potency inhibition of Na(+)-Ca2+ exchange, whereas the NH2-terminal portion is important for the potentiation of the inhibitory activity. Although the IC50 values of various peptides range widely (10(-6)-10(-3) M), all of them induce a complete inhibition. The dose-response pattern of the peptide-induced inhibition is identical for the Na(+)-Ca2+ exchange and its partial reaction, the Ca(2+)-Ca2+ exchange. The inhibitory effect is reversible and affects both Nai(or Cai)-dependent 45Ca uptake and Nao-dependent 45Ca efflux, suggesting that the bidirectional movements of ions are altered. A mild pretreatment of vesicles with trypsin augments the Na(+)-Ca2+ exchange 1.5-fold but diminishes the inhibitory potency 3-4-fold, suggesting that the inhibition is mediated by an extravesicular membrane protein. The characteristics of the peptide-induced inhibition resemble the effect of opiates on Na(+)-Ca2+ exchange. FLRFa and dextrorphan (a non-opioid stereoisomer of an opiate agonist) are mutually exclusive inhibitors, suggesting that they may bind to the same site. This putative site lacks the pharmacological properties of opiate receptors and may be located either on the Na(+)-Ca2+ exchanger or at its vicinity. Endogenous analogs of FMRFa may regulate intracellular calcium via Na(+)-Ca2+ exchange.

Amino Acid Sequence↗
PubMed1993

Cardiac regulation by endogenous small cardioactive peptides and FMRFamide-related peptides in the snail Helix aspersa.

The putative hepatopeptide pQDPFLRIamide, previously known only from its appearance in a cDNA clone from Helix aspersa, was isolated from circumoesophageal ganglia extracts and sequenced. Extracts of several tissues were fractionated by high performance liquid chromatography and the fractions analysed by radioimmunoassay (RIA). The results indicate that ten cardioactive peptides, FMRFamide, FLRFamide, six FMRFamide-related heptapeptides and two nonapeptide analogues of the small cardioactive peptides (SCPs), are present in the circumoesophageal ganglia (brain), the visceral nerve trunk (from which the cardiac nerve branches) and the aorta. The heart contains the two tetrapeptides, FMRFamide and FLRFamide, and the SCPs, but the heptapeptides were completely undetectable in this organ. The levels of tetrapeptide were high enough to allow their calcium-dependent release from the heart to be demonstrated. Immunohistochemistry revealed a diffuse SCP and FMRFamidergic innervation distributed throughout the heart. These data support the idea that, although the ten peptides are probably acting as neurotransmitters throughout most of the cardiovascular system, the heptapeptides probably also have a neurohormonal rôle on the Helix aspersa heart itself. The binding affinities of the various antisera used in these studies were examined in competitive RIAs, in non-competitive dot-blot assays or in both.

Amino Acid Sequence↗
PubMed1992

The localization of FMRFamide in the nervous and somatic tissues of Nereis virens and its effects upon the isolated esophagus.

1. The tetrapeptide FMRFamide which is present in extracts of Nereis virens was localized in various nereid tissues immunohistochemically. 2. Immunoreactive FMRFamidergic cells and fibers were found in the supraesophageal (brain) and subesophageal ganglia, as well as in the intersegmental ganglia of the ventral nerve cord. Immunoreactive fibers were present in the neuropile of, and the connectives between, the supraesophageal, subesophageal, and intersegmental ganglia. 3. In the periphery immunoreactive FMRFamidergic fibers and a few cell bodies were observed in the gut. Sparse fibers were also seen in the body wall, parapodia, and cephalic palps. When the antiserum was preabsorbed with FMRFamide, no specific immunoreactivity was detected. 4. The esophagus of Nereis, isolated and suspended in a tissue bath, responded to FMRFamide with a dose-dependent relaxation; threshold was between 30 and 300 nM, and the EC50 was 1.55 +/- 0.60 microM. Benzoquinonium did not modify this response. 5. Thus, FMRFamide seems to be a neurotransmitter in both the central and peripheral nervous system of Nereis virens, and may be involved in the control of esophageal motility.

Animals↗
PubMed1992

Relationships among the FMRFamide-like peptides.

The nuclear family of FaRPs (comprising those peptides that are, on compelling evidence, homologous) appears to be restricted to the protostome invertebrate phyla: i.e. Mollusca, Arthropoda, Annelida and Nematoda. Neither the origin nor the range of the family has been definitively established. That is, no genuine homologs have been demonstrated yet in the flatworms (though not for lack of trying), and neither the pseudocoelomate phyla related to the nematodes, nor the coelomate relatives of the annelids have been examined. The extended family of FaRPs (including peptides with little consistent sequence similarity beyond a penultimate Arg and an amidated hydrophobic residue at the C-terminal) exists in all phyla. Such a superfamily was probably first proposed by Morris et al. (1982), whose sequencing of SCPB suggested to them a class of peptides, "... the key unit for biological activity being Phe-A-Arg-B-amide (where A and B are also hydrophobic amino acids)." The ubiquity of the convergent FaRPs could reflect a conserved family of complementary heptahelical receptors requiring the arginyl residue for binding (Price and Greenberg, 1989). But another selective advantage would be the protection provided by a penultimate Arg against certain deamidating peptidases, found so far in yeast and mammals (Jackman et al., 1990).

Amino Acid Sequence↗
PubMed1990

Seven FMRFamide-related and two SCP-related cardioactive peptides from Helix.

Pulmonate snails have a more complex array of cardioexcitatory peptides than other molluscs, and Helix has a more complex array than most other pulmonates. Since a full characterisation of the cardioexcitatory peptides is necessary for an understanding of physiology, we sought to identify the members of two families of such peptides - the small cardioactive peptides (SCPs) and the FMRFamide-related peptides (FaRPs) - from Helix aspersa. We characterised the peaks of immunoreactivity from HPLC both by their elution times and by their molecular weights as determined by fast atom bombardment mass spectrometry (FABms). These two criteria, used in parallel, facilitated our identification of several known peptides: MNYLAFPRMamide, identical to SCPB of Aplysia; two tetrapeptide FaRPs, FRMRamide and FLRFamide; and three hepatapeptide FaRPs, NDPFLRFamide, SDPFLRFamide and pQDPFLRFamide. Of these peptides, only FMRFamide and pQDPFLRFamide have previously been reported from Helix. We also discovered an additional SCP and two novel FaRPs and sequenced them. The SCP is Ser-Gly-Tyr-Leu-Ala-Phe-Pro-Arg-Met-amide (SGYLAFPRMamide), and the heptapeptide FaRPs are Asn-Asp-Pro-Tyr-Leu-Arg-Phe-amide (NDPYLRFamide) and Ser-Glu-Pro-Tyr-Leu-Arg-Phe-amide (SEPYLRFamide). When these nine peptides were tested on isolated Helix ventricles, the SCPs were the most potent cardioexcitors, the heptapeptide FaRPs were next, and the tetrapeptides had the least activity.

Amino Acid Sequence↗
PubMed1989

The identification, localization, and pharmacology of FMRFamide-related peptides and SCPB in the penis and crop of the terrestrial slug, Limax maximus.

1. The molluscan neuropeptides FMRFamide, pQDPFLRFamide, and SCPB were tested on the isolated crop and penis of the terrestraial slug, Limax maximus. FMRFamide and pQDPFLRFamide stimulated the penis and inhibited contractions of the crop. In contrast, SCPB either stimulated or relaxed the penis and increased the tone of the crop. 2. Fibers and varicosities containing immunoreactive (ir-) FMRFamide and ir-SCPB were located in the penis and crop. 3. Extracts of penes, crops, ganglia, and whole animals all contained FMRFamide, FLRFamide, SDPFLRFamide, NDPFLRFamide, and pQDPFLRFamide. 4. These results suggest that the FMRFamide-related peptides and SCPB are involved in the regulation of the reproductive and digestive activities of Limax.

Animals↗
PubMed1989

Vasectomy technique.

Vasectomy is a safe and effective method of male sterilization. The procedure and necessary follow-up care can usually be performed in an office setting. Failure of the procedure may be due to incorrect identification of the vas, recanalization or presence of an accessory vas.

Humans↗
PubMed1988

Relationships between the FMRFamide-related peptides and other peptide families.

The relationships between peptide families are recognized in terms of structural similarity and immunological and biological activity. Most of the currently known FMRFamide-related peptides (FaRPs) of molluscs were tested in a radioimmunoassay (RIA) and in the two standard bioassays for FMRFamide: the radula protractor muscle of the whelk Busycon contrarium, and the isolated heart of the clam Mercenaria mercenaria. Some peptides were also tested on the heart of the snail Helix aspersa. The responses of the different assays to these peptides were generally similar, but substantial diversity precluded an absolute resolution of relationships, even among molluscan FaRPs. Nevertheless, this set of responses does constitute a standard against which to estimate the relative affinities of putative FaRPs from other animal groups. Many of the non-molluscan FaRPs (e.g., the pancreatic polypeptide-related peptides, gastrin/CCK, and the opioid peptides) are relatively inactive on the molluscan assays, but others (e.g., LPLRFamide, a peptide isolated from chicken brain; the opioid receptor-modulating peptides A18Fa and F8Fa; and gamma 1-MSH) were relatively potent. Several arthropod FaRPs have substantial FMRFamide-like sequence similarity and immunoreactivity, and they may be homologous members of the molluscan peptide family. However, those structural and functional aspects of peptide families that transcend phyletic lines probably reflect basic principles of binding between peptides and membrane proteins rather than homology.

Amino Acid Sequence↗
PubMed1988

John Henry Welsh: his years, works and flock.

John H. Welsh came down from Boothbay, Maine in the late twenties and landed at Harvard. There he launched his academic career, raised a family, raised an additional family of graduate students and postdoctoral associates, and (with them all) shaped and cultivated diurnal rhythmicity, the biology of neurosecretion, and comparative neuropharmacology. After about 45 yr in the vineyards of Cambridge, he returned to Boothbay and his garden, tree-farm, grandchildren, writings and other good works.

Animals↗
PubMed1988

Prison medicine.

Prisoners in U.S. correctional facilities constitute a unique patient population in need of health services. Physicians who provide medical services to inmates also must interact with prison officials. Drug withdrawal, self-destructive behavior and infectious diseases, including acquired immunodeficiency syndrome, are a few of the challenges to be met.

Acquired Immunodeficiency Syndrome↗
PubMed1987

The actions of FMRFamide-like peptides on visceral and somatic muscles of the snail Helix aspersa.

Phe-Met-Arg-Phe-NH2 (FMRFamide) and pyroGlu-Asp-Pro-Phe-Leu-Arg-Phe-NH2 (pQDPFLRFamide) occur in the ganglia and tissues of the snail, Helix aspersa. This report describes the effects of these two neuropeptides on five visceral organs or somatic muscles isolated from the snail (Table 1). The epiphallus, as well as the rest of the male reproductive tract, was contracted by both FMRFamide and pQDPFLRFamide, and the threshold was usually below 5 X 10(-9) mol l-1 (Fig. 1). Both peptides also reduced the resting tone of the crop and decreased the force and frequency of its rhythmic activity; FMRFamide is about 10 times more potent (Fig. 4). In contrast, pQDPFLRFamide was about 100 times more potent than FMRFamide as a cardioexcitatory agent (Fig. 5). The actions of the peptides on the pharyngeal and tentacle retractor muscles were markedly different: FMRFamide primarily contracted these muscles; and pQDPFLRFamide usually had no effect alone, but relaxed or diminished contractions induced by FMRFamide and acetylcholine (ACh) (Figs 6, 8, 9). Other analogues of FMRFamide were tested, but none was as effective a relaxing agent as pQDPFLRFamide. The effects of FMRFamide and pQDPFLRFamide on all of the preparations could be distinguished from those produced by ACh and 5-hydroxytryptamine (5-HT); thus the actions of the neuropeptides were not mediated by cholinergic or serotonergic neurones. The stimulation of the musculature in the male reproductive tract and the inhibition of motility of the digestive system by FMRFamide and pQDPFLRFamide implicate these peptides in the control of reproductive behaviour. The effectiveness of pQDPFLRFamide in relaxing the retractor muscles and as a cardioexcitatory agent led to the hypothesis that this heptapeptide and FMRFamide, acting at distinct receptors, cooperate to regulate the excitability and contractility of the snail's musculature between the extremes of aestivation and active locomotion.

Acetylcholine↗
PubMed1985

Cross-phyletic bioactivity of arthropod neurohormones and molluscan ganglion extracts: evidence of an extended peptide family.

Two structurally related arthropod neuropeptides, red pigment concentrating hormone (RPCH) and adipokinetic hormone (AKH), are potent excitors of the heart of the clam Mercenaria mercenaria. The response is bimodal: whereas the threshold for affected hearts is 1-3 X 10(-9) M, about 40% of the preparations are virtually unresponsive. Aqueous extracts of Mercenaria ganglia contain a substance which concentrates the red pigment in the erythrophores of intact destalked Uca pugilator and even of its isolated legs. This substance is retained on Sephadex G-15 and co-elutes with synthetic shrimp RPCH. The active fractions also concentrate the erythrophores and the leucophores of destalked shrimp (Penaeus). Neither dopamine nor the molluscan neuropeptide FMRFamide had any chromatophorotropic effect in these assays. The activity of the ganglion extracts was abolished by digestion with chymotrypsin. In conclusion, molluscan ganglion extracts contain a peptide factor, possibly an analog of RPCH, that concentrates the pigments of crustacean chromatophores by a direct action on the cells.

Animals↗