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PubMed1998

Mutant p53 may selectively suppress glial specific proteins in pluripotential human neuroectodermal tumor cells.

The p53 gene is mutated in pluripotential human neuroectodermal tumor DAOY cells which express both glial and neuronal markers. In most cells, nuclear m-p53 immunostaining was intense while cytoplasmic glial specific proteins (GSPs) were present at low levels. Conversely, glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS) were expressed in the few cells devoid of nuclear m-p53 immunoreactivity. The level of neuron specific enolase (NSE) staining was low and not different between p53 positive and p53 negative cells. Therefore, a selective, mutually exclusive expression relationship exists between cytoplasmic GSPs and nuclear m-p53. Upon treatment with epidermal growth factor (EGF) and dibutyrylcyclic AMP, overall cytoplasmic GFAP and GS levels were increased while nuclear p53 was suppressed but a mutually exclusive expression pattern between these proteins was maintained. In cells which also express NSE, GFAP was selectively stimulated suggesting that nuclear expression of m-p53 and cytoplasmic expression of GSPs may be functionally related.

Cytoplasm↗
PubMed1985

Immunoprecipitation of TSH-TSH receptor complexes.

The ability of Graves' sera to interact with the TSH receptor crosslinked to a 125I-labelled photoactive derivative of TSH has been investigated. Crosslinked complexes were prepared using non-purified detergent solubilized human thyroid and guinea pig fat TSH receptors. Affinity purified porcine TSH receptor preparations wee also used. After crosslinking, the crosslinked TSH-TSH receptor complexes were separated from aggregates and free TSH on Sephacryl S-300, incubated with test sera followed by immunoprecipitation using anti-IgG or Protein A. Using non-purified human TSH receptors crosslinked to TSH, a mean +/- SD of 12.1 +/- 4.9% of the crosslinked complex was immunoprecipitated with Graves' sera (n = 7) compared with 10.3 +/- 2.6% with Hashimoto sera (n = 6; P greater than 0.14) and 3.8 +/- 1.0% with normal sera (n = 6; P less than 0.004). These values were markedly reduced when TSH receptor preparations free of other thyroid autoantigens (guinea pig fat TSH receptors) were used. Under these conditions immunoprecipitation with Graves' sera (n = 24) was 1.6 +/- 1.3% compared with 0.8 +/- 0.6% for Hashimoto sera (n = 13) and 0.8 +/- 0.4% for normal sera (n = 12; P less than 0.003). In addition complexes formed between TSH and affinity purified porcine TSH receptors gave low immunoprecipitation values for Graves' (1.44 +/- 0.73%; n = 20) and Hashimoto sera (1.7 +/- 0.94; n = 11) which were not significantly different (P greater than 0.4). Overall, therefore, the effects of Graves' and Hashimoto sera were similar and the amounts of material immunoprecipitated were markedly reduced when TSH receptor preparations containing reduced amounts of other autoantigens were used. Consequently the Graves' sera did not appear to interact specifically with crosslinked TSH-TSH receptor complexes. However the Graves' sera studied did contain TSH receptor antibodies which could inhibit the binding of labelled TSH to TSH receptors in the preparations used and our results suggest that the binding of TSH and these antibodies to the receptor is mutually exclusive. There is considerable evidence that serum from patients with Graves' disease contains antibodies to the TSH receptor (Rees Smith, 1981). Several studies have suggested that binding of the receptor antibody and TSH to the TSH receptor is mutually exclusive (Manley et al., 1977; Petersen et al., 1977; Rickards et al., 1981) but recently the formation of termolecular complexes consisting of detergent solubilized receptors, labelled TSH and Graves' IgG has been reported (Konishi et al., 1982; De Bruin et al., 1984).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Inhibitory and stimulatory effects of structural and conformational analogues of taurine on ATP-dependent calcium ion uptake in the rat retina: deductions concerning the conformation of taurine.

A number of novel analogues of taurine were tested in a rat retinal preparation for their stimulatory or inhibitory activity in the ATP-dependent calcium ion uptake system at low calcium ion concentration. While the structural requirements for maintaining biological activity were quite limited, certain sulfone derivatives of taurine were observed to be more potent stimulators of calcium ion uptake than taurine. Utilization of multiple effectors in the uptake system was also analyzed. The effects of all combinations of taurine plus analogue that were tested were demonstrated to be mutually exclusive, that is, the compounds have similar modes of action. When two inhibitors, TAPS and THQS, were tested in combination, kinetic evaluation of the data suggested that both of these compounds also have a similar mode of action (mutually exclusive) with respect to each other. The inhibitors, TAPS and THQS, were also observed to be non-competitive with respect to taurine thus suggesting that they do not bind to the same site as taurine.

Adenosine Triphosphate↗
PubMed1982

Schizophrenia and psychosomatic illness.

In order to explore the possibility of a mutually exclusive relationship between schizophrenia and certain psychosomatic disorders, 354 adult schizophrenic patients, both acute and chronic, were studied with regard to lifetime prevalence of peptic ulcer, bronchial asthma, neurodermatitis and rheumatoid arthritis. Significant evidence to support the hypothesis of mutual exclusivity was found only in the case of peptic ulcer in the overall sample. Prevalence was higher in younger, more acute patients than in older, chronic patients, but this finding was difficult to interpret. Parallel enquiry into the prevalence of schizophrenia and the same disorders among close family members of the patients yielded inconclusive results.

Adult↗
PubMed1989

Expression of a novel form of the fyn proto-oncogene in hematopoietic cells.

The fyn proto-oncogene encodes a 59-kD membrane-associated protein-tyrosine kinase that is implicated in the control of cell growth. We report here that there are two distinct fyn-encoded transcripts that exhibit mutually exclusive expression patterns; one form is found in thymocytes, splenocytes, and some hematolymphoid cell lines, while a second form accumulates principally in brain. The thymocyte and brain forms of p59fyn differ in their kinase domains, and are generated by mutually exclusive alternative splicing of a single exon. Immunoprecipitation followed by in vitro autophosphorylation demonstrates that both forms of p59fyn are enzymatically active. Our results define a novel form of the p59fyn protein-tyrosine kinase, with an altered catalytic domain, that apparently participates in a specialized signal transduction pathway in hematopoietic cells.

Amino Acid Sequence↗
PubMed1988

Domain of Ultrabithorax expression in Drosophila visceral mesoderm from autoregulation and exclusion.

Domains of differential homeotic gene activity are formed at specific positions along the anteroposterior axis of the early Drosophila embryo. Homeotic genes are required continuously throughout development, so that homeotic gene activity has to be maintained independently of the positional information provided in the early embryo. In the ectoderm, the domains of homeotic gene activity partially overlap, but we have found that in the visceral mesoderm at least three of these genes are expressed in adjacent and mutually exclusive domains. It has been proposed that stable, sharply demarcated domains of this type could be established if a homeotic gene product stimulated its own expression locally and inhibited the expression of other homeotic genes, which Meinhardt has termed autocatalysis and mutual exclusion respectively. Furthermore, autocatalysis of this kind can in principle account for the maintenance of homeotic gene activity throughout development. We find that the unique domain of Ultrabithorax (Ubx) expression in the visceral mesoderm is dependent both on autocatalysis and on an exclusion mechanism: Ubx product is required for its own synthesis, whereas the product of the posteriorly adjacent gene abdominal-A represses Ubx expression.

Animals↗
PubMed2005

Inconsistent probability estimates of a hypothesis: the role of contrasting support.

This paper studies consistency in the judged probability of a target hypothesis in lists of mutually exclusive nonexhaustive hypotheses. Specifically, it controls the role played by the support of displayed competing hypotheses and the relatedness between the target hypothesis and its alternatives. Three experiments are reported. In all experiments, groups of people were presented with a list of mutually exclusive nonexhaustive causes of a person's death. In the first two experiments, they were asked to judge the probability of each cause as that of the person's decease. In the third experiment, people were asked for a frequency estimation task. Target causes were presented in all lists. Several other alternative causes to the target ones differed across the lists. Findings show that the judged probability/frequency of a target cause changes as a function of the support of the displayed competing causes. Specifically, it is higher when its competing displayed causes have low rather than high support. Findings are consistent with the contrastive support hypothesis within the support theory.

Humans↗
PubMed1991

The mystique of the mistake. With proposed standards for validating proficiency tests in anatomic pathology.

Variability in classification in anatomic pathology does not necessarily indicate that a mistake has been made. It is usually an artifact, created when pathologists choose a single category from among two or more justifiable alternatives. This is most common when standard classifications with uniform terminology are not used. It also can occur when classification systems are not constructed so as to insure mutual exclusivity of categories. It is proposed that a proficiency test in anatomic pathology should not be considered scientifically valid until a professional organization primarily concerned with anatomic pathology has endorsed its proposed classification system as having categories that are close to 100% mutually exclusive in the hands of expert pathologists not involved in developing the system. All possible precautions should be taken to insure that the "right answers" for any proficiency test are generated in a way that excludes the possibility of multiple justifiable alternatives.

Clinical Competence↗
PubMed1995

Cardiac myocyte terminal differentiation. Potential for cardiac regeneration.

The exact mechanism of terminal differentiation in cardiac myocytes is currently unknown. Studies in the skeletal muscle system provided a model where muscle lineage termination gene directly interacts with Rb to produce and maintain the terminally differentiated state. This interaction provided the critical components for the lock in cell cycle arrest in skeletal muscle cell. Cardiac muscle appears on the surface very similar to skeletal muscle especially since they share large numbers of structural and contractile proteins. However, it is clear that cardiac muscle cells are distinct biologically at the regulatory level. First and foremost, differentiation and capacity for hyperplasia (mitosis) is not mutually exclusive, in that the heart being the first functional organ embryologically is able to grow via cell division until shortly after birth. Thereafter further growth is provided by hypertrophy. In skeletal muscle, these two processes, differentiation and ability to undergo mitosis, appear to be mutually exclusive. Second, cardiac muscles have not been shown to express any of the skeletal muscle determination basic helix loop helix factors like myoD or any proteins that are functionally similar. Third, heterokaryons of cardiac myocytes and fibroblasts reveal a lack of dominance of the cardiac muscle phenotype. This is distinctly different in skeletal muscle, whose phenotype is dominant which provided a platform to identify the skeletal muscle determination gene, myoD. Although various basic helix loop helix proteins and homeobox genes have been identified in cardiac myocytes, their function remains to be elucidated. At this time no cardiac determination gene has been identified. Despite these differences, we have shown that the biology of pocket proteins Rb and P107 is similar in skeletal and cardiac myocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Analogues of taurine as stimulators and inhibitors of ATP-dependent calcium ion uptake in rat retina: combination kinetics.

Taurine is an amino acid that plays important roles in maintaining both the structural integrity and function of the retina. Thus, the effects of taurine, taurine analogues, and their combinations were studied in the ATP-dependent calcium ion uptake system at low calcium ion concentrations (10 microM) in a rat retinal membrane preparation. (+/-)-(trans)-2-Aminocyclopentanesulfonic acid (TAPS), a cyclic taurine analogue previously determined to inhibit ATP-dependent calcium ion uptake was demonstrated to be noncompetitive (Ki = 0.055 mM) with respect to taurine, that is, the values for the half-saturation concentrations calculated from varying concentrations of taurine compared with varying concentrations of taurine in the presence of a fixed concentration of TAPS (80 microM) did not change. However, the values for the maximal rates of change were significantly different. 1,2,3,4-Tetrahydroquinoline-8-sulfonic acid (THQS), a less potent inhibitor of ATP-dependent calcium ion uptake than TAPS, was also shown to be noncompetitive with taurine, with an inhibition constant (Ki) of 23.8 mM. Thus, it is presumed that both compounds (TAPS and THQS) are acting at receptor site(s) other than the taurine binding site. When TAPS and THQS were tested in a mixture that maintains a ratio (fixed ratio mixture) of 1 part TAPS and 25 parts THQS (by concentration, in mM), varied over a wide range of concentrations, and were then analyzed by median-effect plots and equation, the inhibitory effects are strongly synergistic, as shown by the combination index and the dose-reduction index. The parallel nature of the median-effect plots of TAPS and THQS indicates that the two inhibitors have a similar mode of action, that is, mutually exclusive. (+/-)-3-Aminotetrahydrothiophene-1,1-dioxide (ATS) and (+/-)-piperidine-3-sulfonic acid (PSA) are an agonist and partial agonist that demonstrated stimulatory effects on ATP-dependent calcium ion uptake. When tested in combination (1:1) with taurine, they were also determined to be mutually exclusive. It was demonstrated that ATS and taurine induced the same maximal rates of change of calcium ion uptake; however, PSA was less potent than taurine. The combination of taurine plus ATS was additive, whereas the combination of taurine plus PSA was synergistic. Structure-activity relationships of the taurine analogues and their topological relationships are discussed.

Adenosine Triphosphate↗
PubMed1991

Depression of iron uptake into erythrocytes in mice by treatment with the combined benzene metabolites p-benzoquinone, muconaldehyde and hydroquinone.

Using radio-iron uptake into erythrocytes as a measure of hematopoiesis, it was demonstrated that p-benzoquinone (BQ) and muconaldehyde (MUC) are potent inhibitors of bone marrow function in female mice. These two benzene metabolites reduced iron uptake at dosages of less than 5-6 mg kg-1. The combination of MUC and hydroquinone (HQ) (100 mg kg-1) was additive, reducing iron incorporation to an extent that was the sum of the effect of each chemical given alone. The combined effect of MUC and BQ was significantly less than additive, demonstrating antagonism in the response. Multiple regression was used to study the contributions of the components of binary mixtures of the benzene metabolites (METAB). Data obtained from standard curves of METAB and their mixtures are separable in regression analysis. Thus, for zero interaction of METAB, the responses would be simply additive, while positive and negative interaction would indicate synergy and antagonism, respectively. T-testing of the data resulted in non-significant values for the mixture MUC + HQ, indicating zero interaction and an additive response. The negative t-values obtained for the mixture MUC + BQ, however, indicate negative interaction or an antagonistic response. Since mutually exclusive agents share the same binding sites and occupation of a site by one agent excludes its occupation by another, they cannot interact in producing the effect; combinations of these agents show zero interaction and are simply additive. This suggests that HQ and MUC are mutually exclusive and share the same binding site.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehydes↗
PubMed1994

Mutations in the pre-core region of hepatitis B virus serve to enhance the stability of the secondary structure of the pre-genome encapsidation signal.

We conducted a large-scale survey to determine the frequency and clinical significance of mutations in the pre-core region of hepatitis B virus (HBV). Sera from 263 patients with chronic HBV infection were analyzed by direct sequencing of PCR-amplified HBV DNA. Four major missense/nonsense mutations (M) were found: (M1) C-->T at nucleotide position 1856, Pro-->Ser at codon 15; (M2) G-->A at position 1896, Trp-->stop at codon 28; (M3) G-->A at position 1898, Gly-->Ser at codon 29; and (M4) G-->A at position 1899, Gly-->Asp at codon 29. The commonest conserved mutation was M0: T-->C at position 1858, Pro-->Pro at codon 15. We found that M1 and M2 were mutually exclusive, M3 was only found in association with M1, and M4 was predominantly found in association with M2. All patients with M1 but none of those with M2 had M0. The invariable coexistence of certain mutations in codon 15 and codons 28 and 29 and the mutual exclusion of other mutations in these two noncontiguous regions is related to the stem-loop structure of the pre-genome encapsidation sequence located in the precore/core region. M2 and M4 enhance the stability of the stem by providing two additional paired sites. M1 destroys an existing base pair. However, M1 only occurred in the presence of M0, which provides an extra paired site, and 50% of patients with M1 had M3, a compensatory mutation that restores base pairing at this site. Our data support the proposed secondary structure of the pre-genome encapsidation sequence. The primary function of the mutations in the pre-core region is to enhance stability of this secondary structure to ensure perpetuation of viral replication.

Base Sequence↗
PubMed1994

Theta class glutathione S-transferase GSTT1 genotypes and susceptibility to cervical neoplasia: interactions with GSTM1, CYP2D6 and smoking.

The factors that determine progression of cervical intra-epithelial neoplasia (CIN) to squamous cell carcinoma (SCC) are unknown. Cigarette smoking is a risk factor, suggesting polymorphism at loci that encode carcinogen-metabolizing enzymes such as glutathione S-transferase (GSTT1, GSTM1) and cytochrome P450 (CYP2D6) may determine susceptibility to these cancers. We have studied the frequency of the null genotype at the theta class GSTT1 locus in women with low-grade CIN, high-grade CIN and SCC. The control group comprised women with normal cervical pathology suffering menorrhagia. We found the frequency of GSTT1 null in the control and case groups was not significantly different, though frequency distributions of combinations of the genotype with smoking in mutually exclusive groups in the high-grade CIN group and the other case groups were significantly different. Interactive effects of GSTT1 null with the GSTM1 null and CYP2D6 EM genotypes, and cigarette smoking were also studied by comparing the multinomial frequency distributions of these factors over mutually exclusive categories. These showed no significant differences between the controls and SCC or low-grade CIN. Frequency distributions in high-grade CIN, however, were significantly different to the controls, and both SCC and low-grade CIN; frequency distributions of GSTT1 null with smoking and CYP2D6 EM, individually and in combination, were significantly different. However, inspection of our data does not indicate that GSTT1 null is a major factor mediating risk. Thus, comparison of chi 2 values for the differences between frequency distributions in high-grade CIN and other groups shows that values for combinations of GSTT1 null with other factors are lower than those for equivalent combinations with smoking and CYP2D6 EM. Interestingly, the combination GSTT1 null/GSTM1 null did not appear to influence susceptibility to CIN or SCC.

Adult↗
PubMed1999

Concordant induction of cyclin E and p21cip1 in differentiated keratinocytes by the human papillomavirus E7 protein inhibits cellular and viral DNA synthesis.

Productive infections by human papillomaviruses (HPVs) occur only in differentiated keratinocytes in squamous epithelia in which the HPV E7 protein reactivates the host DNA replication machinery to support viral DNA replication. In a fraction of the differentiated keratinocytes, E7 also posttranscriptionally induces p21Cip1, which is distributed in a mutually exclusive manner with unscheduled cellular DNA synthesis. In this study, double immunofluorescence labeling unexpectedly revealed that E7 caused a concordant accumulation of both cyclin E and p21Cip1 to high levels in patient papillomas and in organotypic cultures of primary human keratinocytes. The induction of cyclin E is mutually exclusive with unscheduled cellular DNA synthesis or abundant viral DNA. These novel virus-host interactions in differentiated keratinocytes are in contrast to previous observations made in submerged proliferating cultures, in which HPV E7 induces cyclin E and overcomes p21Cip1 inhibition of S-phase entry. We propose that an appropriately timed induction of cyclin E/cyclin-dependent kinase 2 by HPV E7 in postmitotic cells enables S-phase reentry and HPV DNA amplification, whereas prematurely induced cyclin E stabilizes p21Cip1 protein, which then inhibits cyclin E/cyclin-dependent kinase 2. Consequently, cyclin E and p21Cip1 both fail to turn over, and DNA synthesis does not occur.

Basal Ganglia↗
PubMed1995

The validity and importance of subtypes in autoimmune hepatitis: a point of view.

OBJECTIVE: To advocate formal subclassification of autoimmune hepatitis into two types based on the presence of mutually exclusive immunoserological markers, target antigen diversity, contrasting genetic predispositions, and differences in clinical profile and behavior. METHODS: Relevant references in English were identified through a Medline Search (1984-1994) and through a personal library of journals and reprints. RESULTS: Antinuclear antibodies and/or smooth-muscle antibodies are mutually exclusive of antibodies to liver/kidney microsome type 1. The cytochrome monooxygenase P450 IID6 is the target autoantigen for patients with antibodies to liver/kidney microsome type 1, and patients with these autoantibodies are different from others. The human lymphocyte antigens DR3 and DR4 are risk factors for patients with antinuclear and/or smooth-muscle antibodies, whereas the B14, DR3, and C4A-QO antigens are common in patients with antibodies to liver/kidney microsome type 1. Patients with antibodies to liver/kidney type 1 are younger, and they more commonly have concurrent organ-specific autoantibodies and/or immunological diseases than counterparts with antinuclear and/or smooth-muscle antibodies. They also progress to cirrhosis more frequently. CONCLUSIONS: Two distinct types of autoimmune hepatitis can be defined by immunoserological markers, genetic predispositions, autoantigen status, and clinical features. Each should be recognized as a valid and independent entity.

Antibody Specificity↗
PubMed2006

The possible role of protein X, a putative auxiliary factor in pathological prion replication, in regulating a physiological endoproteolytic cleavage of cellular prion protein.

The posttranslational conformational conversion of the cellular isoform of prion protein PrP(C) into its scrapie isoform PrP(Sc) is the fundamental process underlying the pathogenesis of prion disease. Based on several transgenic data, it has been postulated that a putative auxiliary factor denoted protein X functions as a molecular chaperone through its unfolding activity of PrP(C) during the formation of PrP(Sc). However, the assumption that protein X therefore exists exclusively in prion diseases appears improbable and thus, it should have some simultaneous physiological role. We, hereby, propose a novel concept - a characteristic role of protein X in supporting a physiological endoproteolytic cleavage of PrP(C). The events corresponding to the formation of the physiologically metabolized PrP(C) or the pathologically transformed PrP(Sc) are mutually exclusive. Amino acid residues that are critical in terms of the target site of protein X for the pathological alteration into PrP(Sc) overlap at the cleavage site. These amino acid residues tend to have a hydrophobic property and are most probably found buried inside the native protein structure. Therefore, a putative molecular chaperone identical to protein X may target the same hydrophobic residues in PrP(C) and work in conjunction with either PrP(Sc) in prion disease or PrP proteases during the physiological state. This postulation may help explain in a relatively simple manner these two mutually exclusive phenomena, viz. the physiological endoproteolytic cleavage of PrP(C) and its pathological conversion into PrP(Sc).

Animals↗
PubMed1982

Interaction of monoclonal antibodies with mammalian choline acetyltransferase.

Monoclonal antibodies selective for rat brain choline acetyltransferase (acetyl-CoA: choline O-acetyltransferase, EC 2.3.1.6) were prepared by standard techniques. Five cell lines were isolated from spleen cell-SP/2 hybrids by repetitive cloning with a screening method that used the intrinsic activity of the enzyme. All cell lines secrete immunoglobulin of mouse subclass IgGl, and none inhibit the enzyme activity directly. The size of antibody-enzyme immune complexes formed with different pairs of the monoclonal antibodies was determined by gel filtration with HPLC. By comparing the elution position of choline acetyl-transferase activity after incubation with paired monoclonal antibodies, the spatial relationship of antibody binding domains relative to each other can be defined and classified as independent, mutually exclusive, or overlapping. Immune complexes in excess of Mr 600,000 were formed by some pairs of antibodies with the antigen, indicating independent binding domains on the enzyme. In one case, the paired antibodies formed an immune complex of only Mr 300,000, indicating that they bound in a mutually exclusive fashion. In most cases, pairs of antibodies reacted with the enzyme to give simultaneously both higher and lower Mr immune complexes. We conclude that all five antibodies bind to a relatively localized region of the enzyme surface. Antibodies were screened for usefulness as immunohistochemical markers of choline acetyltransferase-containing neurons by using the indirect immunoperoxidase method. One antibody intensely stains cell bodies of motor neurons and processes in a selective manner in the rat spinal cord and brain stem by using aldehyde-fixed tissue; the remaining antibodies do not react with fixed tissue.

Animals↗
PubMed1998

Matrix-assisted laser desorption/ionization time of flight mass spectrometric analysis of the pattern of peptide expression in single neurons resulting from alternative mRNA splicing of the FMRFamide gene.

MALDI-ToF MS (matrix-assisted laser desorption/ionization time of flight mass spectrometry) has become a fast, reliable and sensitive technique for the identification of neuropeptides in biological tissues. Here, we applied this technique to identified neurons of the cardioregulatory network in the snail Lymnaea that express the FMRFamide gene. This enabled us to study the complex processing of the FMRFamide gene at the level of single identified neurons. In the CNS of Lymnaea, FMRFamide-like and additional peptides are encoded by a common, multiexon gene. Alternate mRNA splicing of the FMRFamide gene leads to the production of two different mRNAs. Type 1 mRNA (exon II) encodes for the tetrapeptides (FLRF/FMRFamide), whereas Type 2 (exons III-V) encodes for the heptapeptides (SDPFLRFamide/GDPFLRFamide). Previous in situ hybridization and immunocytochemical studies indicated that these two transcripts are expressed in the CNS neurons of Lymnaea in a differential and mutually exclusive manner. Two single identified neurons of the cardiorespiratory network, the Ehe neuron and the visceral white interneuron (VWI), were known to express the FMRFamide gene (Ehe, type 1 mRNA; VWI, type 2 mRNA). MALDI-ToF MS analysis of these neurons and other neurons expressing the FMRFamide gene confirmed the mutually exclusive expression of the distinct sets of peptides encoded on the two transcripts and revealed the pattern of post-translational processing of both protein precursors. From the gene sequence it was predicted that 16 final peptide products from the two precursor proteins could possibly exist. We showed that most of these peptides were indeed present in the identified neurons (13) while others were not (three), suggesting that not all of the potential cleavage sites within the two precursors are utilized. In this way, the neuronal expression of the full range of the peptide products resulting from alternative mRNA splicing was revealed for the first time.

Alternative Splicing↗