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PubMed1980

Stability of sex chromosome mosaicism.

In individuals with sex chromosome mosaicism the proportions of cell lines have been reported to change over time; however, purported changes have failed to show a consistent decrease or increase in any given cell line, normal or abnormal. We, therefore, investigated three mosaic individuals: two 45,X/46,X,i(Xq) and one 45,X/46,XX. We first initiated studies which verified that the proportion of various cell lines can be reliably (reproducibly) quantitated in lymphocytes of mosaic individuals, data which surprisingly were heretofore unavailable. Having established the ability to quantitate sex chromosome mosaicism, we initiated longitudinal studies. No significant differences in proportions of mosaic cell lines were observed in the three individuals studied over various time intervals. This stability was observed in individuals with high as well as lower proportions of 45,X cells. Further studies over longer periods and with other subjects are continuing, but our preliminary studies suggest mosaicism shows longitudinal stability, at least in adults. The practical clinical significance is that mosaicism can be reproducibly quantitated from a single lymphocyte culture, indicating that a single blood sample will generally suffice for most clinical studies.

Adolescent↗
PubMed2004

Mechanism of recurrent spontaneous abortions in women with mosaicism of X-chromosome aneuploidies.

OBJECTIVE: To investigate the mechanism of recurrent miscarriages in women with mosaicism of X-chromosome aneuploidies. DESIGN: Prospective case-control study. SETTING: University-based reproductive clinic housed in a medical center with genetic laboratories. PATIENT(S): Eighteen women who experienced recurrent miscarriages and had mosaicism of X-chromosome aneuploidies; two control groups, one with a balanced structural autosomal rearrangement and the other without chromosomal abnormalities. INTERVENTION(S): Criteria were established for the diagnosis of low-grade X-chromosome mosaicism by using peripheral blood lymphocytes. Patients were evaluated for the pathogenesis of recurrent miscarriages. Their abortion rate was assessed, and each abortus was karyotyped. MAIN OUTCOME MEASURE(S): Abortion rate and karyotype of the abortus. RESULT(S): In comparison with patients with X-chromosome mosaicism with a balanced structural autosomal rearrangement, patients with X-chromosome mosaicism without a balanced autosomal structural rearrangement had a significantly higher incidence of diminished ovarian reserve (DOR) and had a somewhat higher prevalence of uterine anomalies. In comparison with controls without chromosomal abnormalities, the patients with a balanced autosomal structural rearrangement also had higher incidence of both conditions, but the differences were not statistically significant. At least two factors are implicated in recurrent miscarriages in women with X-chromosome mosaicism. Among them, DOR is the most prevalent (occurring in 44.4% of cases), followed by uterine anomalies (16.7% of cases). Cases with DOR had a higher abortion rate than did those without (68.6% vs. 44.1%). Cases with DOR also had a slightly higher rate of abnormal karyotypes in the abortus than did those without (73.7% vs. 42.9%). CONCLUSION(S): The oocytes of women with X-chromosome mosaicism are in a suboptimal state of development and are prone to embryonic lethality.

Abortion, Habitual↗
PubMed2006

Modern mosaic analysis in the zebrafish.

One of the most powerful tools used to gain insight into complex developmental processes is the analysis of mosaic embryos. A mosaic is defined as an organism that contains cells of more than one genotype, usually wild-type and mutant. It is the interplay between wild-type and mutant cells in the mosaic that reveals information about the normal function of the mutated gene. Mosaic analysis has been utilized extensively in Caenorhabditis elegans, Drosophila, mice, and zebrafish to elucidate when, where, and how a gene acts during development. In the zebrafish, mosaic analysis has been used to dissect a number of different developmental processes, including gastrulation movements, mesoderm and endoderm specification, neuronal patterning and migration, axon pathfinding, angiogenesis, and cardiac, retinal, and neural crest development. Mosaic analysis is a particularly effective method for understanding gene function in the zebrafish, a model organism particularly suited to forward genetic, molecular, and classical embryological approaches. These attributes, when combined with the accessibility and optical clarity of the zebrafish embryo, facilitate the real time observation of individual cell behaviors and interactions within mosaic embryos.

Animals↗
PubMed1998

Induction of mosaic sex-linked recessive lethals in the different germ cell stages of Drosophila melanogaster by bleomycin.

The mutagenicity of bleomycin was studied in the different stages of spermatogenesis in Drosophila melanogaster. Following the injection of 2 microliters of 0.1 micrograms/ml of the chemical into young wild-type males, complete and mosaic sex-linked recessive lethals were scored by the Muller-5 method in five successive broods, mainly representing the different stages of spermatogenesis. The delayed mutagenic effect of the chemical was measured by the proportion of mosaic progeny produced. The results showed that bleomycin significantly increased the proportions of both complete and mosaic lethals in the broods representing the meiotic and pre-meiotic stages, but did not show any significant increase in these proportions in the broods representing the sperms and spermatids. The sizes of the mutated areas in the F1 gonads represented by the proportions of lethal-bearing females in F2 mosaic cultures were small, indicating that the genetic instabilities induced by bleomycin were transformed into actual mutations in later zygotic divisions. The significant divisions. The significant production of mosaic progeny in the F4 generation of the treated males showed that the mosaic F1 females produced by bleomycin were able to produce further mosaic progeny and suggested that bleomycin-induced instabilities can be transmitted as such for many future generations.

Animals↗
PubMed2003

Retinoblastoma associated with chromosomal 13q14 deletion mosaicism.

PURPOSE: To assess the risk of retinoblastoma developing in children with microscopic chromosomal with mosaic deletions involving 13q14. DESIGN: Case report and systematic literature review. PARTICIPANTS: Data on 29 patients with a mosaic and 107 patients with a nonmosaic somatic deletion of chromosome 13q14 were compared. MAIN OUTCOME MEASURES: Age at diagnosis, frequency, and laterality of retinoblastoma. CASE REPORT: A dysmorphic baby, who carried a chromosomal deletion involving 13q14 in 34% of peripheral blood lymphocytes, had neuroradiologic evidence of retinoblastoma at the age of 2 weeks. She developed trilateral retinoblastoma, a pineal neuroblastic tumor, at the age of 10 months. The diagnosis of her tumor was delayed because of misjudgment of risk of retinoblastoma developing. RESULTS: Meta-analysis revealed no difference between children with mosaic and nonmosaic chromosomal deletion of 13q14 regarding the age at diagnosis, laterality of tumor, and presence of family history for retinoblastoma. A lower percentage of somatic cells with mosaic deletion did not predict a higher age at diagnosis or unilateral tumors. No statistically significant difference was noted regarding the presence of mental retardation, dysmorphic features, and anomalies of internal organs between mosaic and nonmosaic deletions. Only 7% (95% confidence interval, 1-23) of 29 patients who had a mosaic chromosomal deletion including 13q14 were not reported to develop retinoblastoma. CONCLUSIONS: Whenever a 13q14 deletion is diagnosed, immediate ophthalmologic evaluation is recommended to ensure prompt diagnosis of retinoblastoma. Mosaic and nonmosaic chromosomal deletions of 13q14 do not differ regarding the risk and type of retinoblastoma developing.

Brain Neoplasms↗
PubMedDate not supplied

Large retinal ganglion cells that form independent, regular mosaics in the ranid frogs Rana esculenta and Rana pipiens.

Population-based studies of ganglion cells in retinal flatmounts have helped to reveal some of their natural types in mammals, teleost fish and, recently, the aquatic mesobatrachian frog Xenopus laevis. Here, ganglion cells of the semiterrestrial neobatrachian frogs Rana esculenta and Rana pipiens have been studied similarly. Ganglion cells with large somata and thick dendrites could again be divided into three mosaic-forming types with distinctive stratification patterns. Cell dimensions correlated inversely with density, being smallest in the visual streak. Cells of the alpha a mosaic (< 0.2% of all ganglion cells) had the largest somata at each location (often displaced) and their trees were confined to one shallow plane within sublamina a of the inner plexiform layer. In regions of high regularity, many trees were symmetric. Elsewhere, asymmetric, irregular trees predominated and their dendrites, although sparsely branched, achieved consistent coverage by intersecting in complex ways. Cells of the alpha ab mosaic were more numerous (approximately 0.7%) and had large somata, smaller (but still large) trees, and dendrites that branched extensively in two separate shallow planes in sublaminae a and b. The subtrees did not always match in symmetry, and each subtree tessellated independently with its neighbors. Cells of the alpha c mosaic (approximately 0.1%) had large, orthotopic somata and large, sparse trees (often asymmetric and irregular) close to the ganglion cell layer. Nearest-neighbor analyses and spatial correlograms confirmed that each mosaic was regular and independent. Densities, proportions, sizes, and mosaic statistics are tabulated for all three types, which are compared with types defined by size and symmetry in R. pipiens, by discriminant analysis in R. temporaria, by physiological response in both, and by mosaic analysis in Xenopus and several teleosts. The variable stratification of these otherwise similar types across species is consistent with other evidence that stratification may be determined, in part, by functional interactions.

Animals↗
PubMed2000

Analysis of sex chromosome aneuploidy in 41 patients with Turner syndrome: a study of 'hidden' mosaicism.

We performed a genetic study of sex chromosome mosaicism in 41 Turner syndrome patients. The investigation was carried out in four phases: cytogenetics (G-banding), FISH, PCR for SRY in all 41 cases, and sequencing of the SRY gene in the 2 patients with the Y chromosome. The application of classical alpha-satellite probes (CEP-X and CEP-Y), painting probes (WCP-X and WCP-Y) and also XIST, DXZ4 and two subchromosomal painting libraries (SCPL 116 and SCPL102) covering the short and the long arm of the X chromosome, respectively, allowed us to find new mosaic cell lines (mosaicism) in 37 out of 41 patients; only 4 patients were defined as 45,X non-mosaic. The most frequent hidden mosaic was 45,X/46,XX in 32% of the cases; the presence of isochromosomes comprised 25% and markers 5%. The patients who had been previously diagnosed as mosaics displayed a higher complexity in their karyotypes due to the presence of new cell lines. The Y chromosome and the SRY gene were present in blood and ovarian tissue in 2 patients with karyotypes 45,X/46,XY and 45,X/46,X,idic(Ynf). In both patients, the sequencing of the SRY gene confirmed a nucleotide sequence identical to that of a control male. Our results support the hypothesis of 'the necessity of mosaicism for survival', and thus, a mitotic origin for this syndrome.

Aneuploidy↗
PubMed2001

Somatic mosaicism in hemophilia A: a fairly common event.

Mutations in the large gene of clotting factor VIII (FVIII) are the most common events leading to severe human bleeding disorder. The high proportion of de novo mutations observed in this gene raises the possibility that a significant proportion of such mutations does not derive from a single germ cell but instead should be attributed to a germline or somatic mosaic originating from a mutation during early embryogenesis. The present study explores this hypothesis by using allele-specific PCR to analyze 61 families that included members who had sporadic severe hemophilia A and known FVIII gene defects. The presence of somatic mosaicisms of varying degrees (0.2%-25%) could be shown in 8 (13%) of the 61 families and has been confirmed by a mutation-enrichment procedure. All mosaics were found in families with point mutations (8 [25%] of 32 families). In the subgroup of 8 families with CpG transitions, the percentage with mosaicism increased to 50% (4 of 8 families). In contrast, no mosaics were observed in 13 families with small deletions/insertions or in 16 families with intron 22 inversions. Our data suggest that mosaicism may represent a fairly common event in hemophilia A. As a consequence, risk assessment in genetic counseling should include consideration of the possibility of somatic mosaicism in families with apparently de novo mutations, especially families with the subtype of point mutations.

Alleles↗
PubMed2004

High frequency of mosaicism among patients with neurofibromatosis type 1 (NF1) with microdeletions caused by somatic recombination of the JJAZ1 gene.

Detailed analyses of 20 patients with sporadic neurofibromatosis type 1 (NF1) microdeletions revealed an unexpected high frequency of somatic mosaicism (8/20 [40%]). This proportion of mosaic deletions is much higher than previously anticipated. Of these deletions, 16 were identified by a screen of unselected patients with NF1. None of the eight patients with mosaic deletions exhibited the mental retardation and facial dysmorphism usually associated with NF1 microdeletions. Our study demonstrates the importance of a general screening for NF1 deletions, regardless of a special phenotype, because of a high estimated number of otherwise undetected mosaic NF1 microdeletions. In patients with mosaicism, the proportion of cells with the deletion was 91%-100% in peripheral leukocytes but was much lower (51%-80%) in buccal smears or peripheral skin fibroblasts. Therefore, the analysis of other tissues than blood is recommended, to exclude mosaicism with normal cells in patients with NF1 microdeletions. Furthermore, our study reveals breakpoint heterogeneity. The classic 1.4-Mb deletion was found in 13 patients. These type I deletions encompass 14 genes and have breakpoints in the NF1 low-copy repeats. However, we identified a second major type of NF1 microdeletion, which spans 1.2 Mb and affects 13 genes. This type II deletion was found in 8 (38%) of 21 patients and is mediated by recombination between the JJAZ1 gene and its pseudogene. The JJAZ1 gene, which is completely deleted in patients with type I NF1 microdeletions and is disrupted in deletions of type II, is highly expressed in brain structures associated with learning and memory. Thus, its haploinsufficiency might contribute to mental impairment in patients with constitutional NF1 microdeletions. Conspicuously, seven of the eight mosaic deletions are of type II, whereas only one was a classic type I deletion. Therefore, the JJAZ1 gene is a preferred target of strand exchange during mitotic nonallelic homologous recombination. Although type I NF1 microdeletions occur by interchromosomal recombination during meiosis, our findings imply that type II deletions are mediated by intrachromosomal recombination during mitosis. Thus, NF1 microdeletions acquired during mitotic cell divisions differ from those occurring in meiosis and are caused by different mechanisms.

Adolescent↗
PubMed1991

Reciprocal phenotype alterations between two satellite RNAs of cucumber mosaic virus.

Cucumber mosaic virus Y satellite RNA (Y-satRNA) induces distinctive yellow mosaic symptoms on tobacco, whereas S19 satellite RNA (S19-satRNA) causes an attenuated green mosaic on tobacco, although they show considerable sequence identity. Biological assays of infectious chimeric satellite RNA molecules synthesized from cDNA clones of Y-satRNA and S19-satRNA using common restriction sites showed that the determinant for the induction of yellow mosaic symptoms lies in the BstXI-NheI fragment, in which 14 nucleotide differences are found between the two satellite RNAs. To define more precisely the yellow mosaic determinant(s) in this fragment, several site-directed mutants of Y-satRNA were created. The replacement of AUU, at nucleotides 191 to 193 in Y-satRNA, with GC, which mimics the S19-satRNA sequence at the corresponding site, abolished the ability of Y-satRNA to elicit a yellow mosaic. Conversely, a mutant RNA molecule derived from S19-satRNA in which GC at nucleotides 192 and 193 was changed to AUU induced the yellow mosaic symptoms. Thus, the phenotypes of two satellite RNAs on tobacco can be altered reciprocally by changing the sequences in this limited region.

Base Sequence↗
PubMed2003

Molecular study of frequency of mosaicism in neurofibromatosis 2 patients with bilateral vestibular schwannomas.

Neurofibromatosis 2 (NF2) is a severe autosomal dominant disorder that predisposes to multiple tumours of the nervous system. About half of all patients are founders with clinically unaffected parents. The purpose of the present study was to examine the extent to which mosaicism is present in NF2 founders. A total of 233 NF2 founders with bilateral vestibular schwannomas (BVS) were screened by exon scanning. NF2 mutations were detected in the blood samples of 122 patients (52%). In 10 of the 122 cases, the ratio of mutant to normal alleles was obviously less than 1, suggesting mosaicism. Tumour specimens were available from 35 of the 111 subjects in whom no mutation could be detected in blood specimens. Mutational analysis by exon scanning detected typical NF2 mutations in 21 of the 35 tumours. In nine subjects, the alterations found in tumours could be confirmed to be the constitutional mutation based on finding of identical mutations in pathologically and/or anatomically distinct second tumours. In six other subjects with only a single tumour available, allelic loss of the NF2 gene was found in addition to the mutation in each tumour, suggesting that either the mutation or the deletion of the NF2 gene is probably the constitutional genetic alteration. Our results suggest that failure to find constitutional mutations in blood specimen from these 15 patients was not because of the limitation of the applied screening technique, but the lack of the mutations in their leucocytes, best explained by mosaicism. Extrapolating the rate (15/35 = 43%) of mosaicism in these 35 cases to the 111 NF2 founders with no constitutional NF2 mutations found in their blood, we inferred 48 mosaic subjects (111 x 0.429). Adding the 10 mosaic cases detected directly in blood specimens, we estimate the rate of mosaicism to be 24.8% (58/233) in our cohort of 233 NF2 founders with bilateral vestibular schwannomas.

Base Sequence↗
PubMed1987

Abnormally high variability in the uncrossed retinofugal pathway of mice with albino mosaicism.

Female mice showing albino mosaicism due to an X-autosome translocation [Is(In7;X)Ct] have been studied in order to investigate the relationship between the distribution of melanin and the formation, early in development, of the abnormally small uncrossed retinofugal pathway characteristically found in all albino mammals. Earlier evidence indicates that cells normally bearing melanin play a role in producing the abnormality. In the mosaic mice, the albino gene is expressed in only about half of the cells due to random X-inactivation and the patches of normal and albino cells are extremely small relative to total retinal size (less than 1/50). We argued that if all the cells that would normally bear melanin play a role in producing the albino abnormality then the mosaic mice would have a pathway abnormality, about half the size of that in the albino mice. If, however, only a small patch of these cells plays a role, as has been proposed in earlier studies, then one would expect the size of the uncrossed pathway to be highly variable in the mosaic mice. The size of the uncrossed pathway was assessed by placing horseradish peroxidase in the region of the optic tract and lateral geniculate nucleus unilaterally and then counting the number of retrogradely labelled retinal ganglion cells on the same side. The mosaic mice showed a highly variable uncrossed pathway. In some of the mosaic mice, it was the same size as in the albinos and, in others, it was the same size as in normally pigmented mice. Surprisingly, in a small number of mosaic mice, the uncrossed pathway was larger than normal. Whether this relatively rare occurrence of a supernormal uncrossed pathway is due to the higher gene dosage or to the translocation itself remains an open question.

Albinism↗
PubMed1987

A probabilistic model of mosaicism based on the histological analysis of chimaeric rat liver.

The analysis of pattern development in mosaic and chimaeric animals has provided insight into a number of developmental problems. In order to aid the understanding of the dynamics of the development of mosaic tissues, a computer simulation of the generation of a mosaic tissue was created using simple probabilistic decisions. Results of quantitative analysis of the simulated mosaicism were compared with chimaeric liver. Chimaeric animals were produced by morula aggregation between histologically distinguishable strains of congenic rats. The livers of these animals revealed a pattern of patchy mosaicism unrelated to either acinar or lobular architecture of the organ. Independent quantifiable parameters were correlated and compared between the simulation and chimaeric liver tissue. This analysis showed that extensive cell migration is not required to develop finely variegated mosaic tissue and that the patterns of mosaicism observed could have resulted from tissue development in which as few as three reiterated decisions were required. First, the simulation established anlagen of two cell types of various specified proportions with randomly chosen placement. Second, in each generation of the simulation the order in which the cells divided was established randomly. Third, there was a random choice of the direction of placement of the daughter cell. The quantitative relationships between the proportion of cell types, the area of patches and the number of patches per unit area was consistent between the simulation and the chimaeric tissue.

Animals↗
PubMed1993

X chromosome mosaicism in patients with recurrent abortion or premature ovarian failure.

X chromosome mosaicism is usually associated with abnormal sexual development and reproductive performance, such as recurrent spontaneous abortion, primary or secondary amenorrhea, infertility, and premature ovarian failure. However, there is a paucity of literature which discusses these relationships. From July 1988 to December 1992, a total of 105 couples with a history of recurrent spontaneous abortion from a genetic counseling clinic and 61 women with a history of premature ovarian failure followed up in reproductive endocrinology clinics were assembled, and chromosomal analysis of peripheral blood lymphocytes was carried out. X chromosome mosaicism was found in six individuals (2.9%) out of the 105 couples with recurrent spontaneous abortion, and in five (8.2%) out of 61 women with premature ovarian failure. The karyotypes were 45,X/46,XX/47,XXX in five cases, 45,X/46,X in four cases, and 46,XX/47,XXX in two cases. The cases of complex X chromosome mosaicism (45,X/46,XX/47,XXX) presented recurrent spontaneous abortion in four cases and premature ovarian failure in one case. The cases of mosaic Turner's syndrome (45,X/46,XX) presented premature ovarian failure in three cases and recurrent spontaneous abortion in one case. The two cases of mosaic triple-X syndrome (46,XX/47,XXX) presented with premature ovarian failure and recurrent spontaneous abortion, respectively. However, the ratio of mosaic cell lines does not correlate well with the phenotypic manifestations in our cases. Our preliminary data suggest that chromosomal analysis should be done routinely in every couple with recurrent spontaneous abortion and in women with premature ovarian failure. The reproductive performance of X chromosome mosaicism is highly variable and difficult to define.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Habitual↗
PubMed1993

Mosaicism in chorionic villus sampling.

Although chromosomal mosaicism is encountered frequently in CVS, it is most often restricted to the extraembryonic tissues. Counseling before CVS should include a discussion of the frequency and significance of placental mosaicism. Patients seeking information about the procedure need to be aware of the slight but not negligible possibility of the need for additional follow-up studies. Additional studies may involve additional risks with emotional and psychological sequelae. Ultimately, no prenatal procedure or combination of procedures can provide 100% accuracy in excluding mosaicism once the issue has been raised. When the mosaicism is felt to be confined to the placenta, counseling should probably address the potential increased risk for pregnancy complication, such as miscarriage and IUGR, with appropriate follow-up of the pregnancy, especially in the third trimester. Excluding the issue of mosaicism, the predictive value of cytogenetic diagnosis after CVS is equivalent to that of amniocentesis. In addition, CVS provides this information at an earlier time in the pregnancy than does amniocentesis. The majority of patients electing CVS (98% or more) will not have to deal with these complicated issues. It is hoped that an increasing cumulative experience with CVS mosaicism will help differentiate low- from high-risk situations. At the present time, however, there are insufficient and inconsistent data with which to accurately assess the risks associated with placental mosaicism. Most of the available literature concludes that additional, more focused studies, including long-term follow-up, are needed to help elucidate a better understanding of these issues.

Chorionic Villi Sampling↗
PubMed1997

Mosaic trisomy 22: a case presentation and literature review of trisomy 22 phenotypes.

In a case of mosaic trisomy 22 the trisomic cells were detected primarily in fibroblasts. Results of initial lymphocyte chromosome analysis were normal. However, mosaicism was suspected because the patient had hypomelanosis of Ito, hemiatrophy, failure to thrive, and mental retardation. Mosaicism was confirmed in cultured fibroblasts. Repeat cytogenetic analysis of peripheral blood demonstrated a low level of trisomic metaphase cells, which was confirmed by interphase fluorescent in situ hybridization (FISH) analysis. Molecular studies supported maternal disomy in the child's disomic cells. The phenotype of this condition overlaps that of non-mosaic trisomy 22 chromosome mosaicism in general and to some extent the Ullrich-Turner syndrome phenotype. Improved cytogenetic and molecular techniques now allow better delineation of aneuploidy syndromes. Molecular and FISH studies added information about this case (mosaicism and uniparental disomy) not appreciated by routine cytogenetic analysis of lymphocytes. The detection of low-level mosaicism and/or uniparental disomy in such cases may change the clinical classification and our understanding of pathogenesis and recurrence risk of these disorders.

Adult↗
PubMed1997

Mosaics of islet-1-expressing amacrine cells assembled by short-range cellular interactions.

The nervous system has a modular architecture with neurons of the same type commonly organized in nonrandom arrays or mosaics. Modularity is essential to parallel processing of sensory information and has provided a key element for brain evolution, but we still know very little of the way neuronal mosaics form during development. Here we have identified the immature elements of two retinal mosaics, the choline acetyltransferase (ChAT) amacrine cells, by their early expression of the homeodomain protein Islet-1, and we show that spatial ordering is an intrinsic property of the two Islet-1 mosaics, dynamically maintained while new elements are inserted into the mosaics. Migrating Islet-1 cells do not show this spatial ordering, indicating that they must move tangentially as they enter the mosaic, under the action of local mechanisms. Clonal territory analysis in X-inactivation transgenic mice confirms the lateral displacement of ChAT amacrine cells away from their clonal columns of origin, and mathematical models show how short-range cellular interactions can guide the assemblage of these mosaics via a simple biological rule.

Animals↗
PubMed1992

Mosaic distribution of phosphate-activated glutaminase-like immunoreactivity in the rat striatum.

The dorsal and ventral striatum of mammals has been known to be organized in a mosaic manner, referred to as "patches" and "matrix" of the caudatoputamen. The present study was primarily attempted in order to reveal the relationship of glutamatergic neuronal components to the mosaic organization in the rat striatum by using a monoclonal antibody to phosphate-activated glutaminase, a major synthetic enzyme of transmitter glutamate. Antibodies against glutamate decarboxylase and choline acetyltransferase were also used as the markers for GABAergic and cholinergic neuronal components, respectively. Glutaminase immunoreactivity was seen in a number of large- and a few medium-sized neurons in the caudatoputamen, nucleus accumbens and olfactory tubercle. The large neurons with glutaminase immunoreactivity were observed in the neuropil of the caudatoputamen and nucleus accumbens; glutaminase immunoreactivity was particularly marked in the neuropil of island-like patchy areas although it was seen throughout the neuropil of the nuclei. In the caudatoputamen, island-like areas with marked glutaminase immunoreactivity exhibited less marked choline acetyltransferase immunoreactivity than the surrounding background region, and were thus considered to correspond to the patches. The mosaic distribution of glutamate decarboxylase immunoreactivity in the caudatoputamen seemed identical with that of glutaminase immunoreactivity. However, in the nucleus accumbens, the mosaic pattern of neuropil labeling for glutaminase was neither consistent with that for glutamate decarboxylase nor that for choline acetyltransferase, suggesting the presence of non-GABAergic glutaminase-containing nerve terminals in the nucleus. In an attempt to clarify the origin of neuropil labeling for glutaminase in the striatum, lesions were made in the regions sending projection fibers to the caudatoputamen and nucleus accumbens. After placing lesions in the cerebral cortex, glutaminase immunoreactivity was decreased in neuropil of the caudatoputamen, but the mosaic pattern remained. Lesions which were placed in the intralaminar thalamic nuclei, amygdaloid body, globus pallidus or substantia nigra produced no substantial change in glutaminase immunoreactivity in the caudatoputamen and nucleus accumbens. After injection of kainic acid into the caudatoputamen or nucleus accumbens, glutaminase immunoreactivity in the neuropil of the affected regions was decreased to lose the mosaic pattern, indicating that neuronal components with glutaminase immunoreactivity in the neuropil of the patches were mainly of intrinsic origin. In summary, possible axon terminals containing glutaminase were observed with mosaic patterns in the caudatoputamen and nucleus accumbens, in which large cholinergic and medium-sized non-cholinergic neurons were immunoreactive for glutaminase. In the caudatoputamen, glutaminase immunoreactivity in neuropil was more marked in the patches than in the matrix.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗