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Results for “molecular features”

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PubMed2003

Differences in the pathologic and molecular features of intraductal breast carcinoma between younger and older women.

BACKGROUND: Patients diagnosed with ductal carcinoma in situ (DCIS) at a young age appear to have a different natural history and biology, including a higher local relapse rate, than patients diagnosed later in life. The current study compared various pathologic and molecular features of DCIS arising in a cohort of young women with those of DCIS arising in a cohort of older women to identify potential biologic differences between these two populations of patients. METHODS: The study population consisted of 20 patients age < 42 years and 34 patients age > 60 years who were treated at Yale University School of Medicine with breast-conserving therapy (BCT) and whose archival paraffin blocks were available and had sufficient tumor for staining. The original slides from each case were reviewed and the most representative specimen block from each case was processed for immunohistochemical staining. Pathologic characteristics evaluated for each case included histology, grade, and presence of necrosis. Paraffin-embedded sections were immunohistochemically evaluated for expression of HER-2/neu, estrogen receptor (ER), progesterone receptor (PR), bcl-2, cyclin D1, Ki-67, and p53. RESULTS: Although there was no difference in pathologic features of the tumors between the two groups, HER-2/neu was found to be overexpressed in a greater percentage of the younger population (P = 0.06). There was no apparent difference in expression of the other markers. Of note, HER-2/neu expression was correlated with high nuclear grade (P = 0.004), necrosis (P = 0.06), and ER and PR negativity (P = 0.01 and P = 0.03, respectively) in the combined population. CONCLUSIONS: The current study data suggested that HER-2/neu overexpression in younger patients may characterize a biologic difference in their tumor and may partially contribute to their higher risk of recurrence. Further studies are needed to assess whether this difference holds independent of grade and to evaluate the prognostic significance of HER-2/neu overexpression in DCIS.

Adult↗

PubMed2002

Primary thymic extranodal marginal-zone B-cell lymphoma of mucosa-associated lymphoid tissue type exhibits distinctive clinicopathological and molecular features.

Extranodal marginal-zone B-cell lymphoma (MZBL) of mucosa-associated lymphoid tissue (MALT) arising in the thymus is rare, with the largest series in the literature including only three cases. In the present study, we investigated 15 cases of thymic MALT lymphoma to systematically characterize its clinical, histopathological, and molecular features. There was a marked female predilection (male:female = 1:4), with a mean age of 55 years at diagnosis. There was a strong association with autoimmune disease, especially Sjögren's syndrome. Histologically, the thymic lymphoma showed the characteristic morphological features of extranodal MZBL of MALT type. Cysts were common. Prominent lymphoepithelial lesions were formed by centrocyte-like cells infiltrating and expanding the Hassall's corpuscles and epithelium lining the cysts. Plasmacytic differentiation was apparent in all cases. Notably, 13 of 15 cases expressed immunoglobulin (Ig) A phenotype; IgA expression in thymic MALT lymphoma was in striking contrast with the IgM phenotype observed in most of the Sjögren's syndrome-associated MZBLs and MALT lymphomas at other sites. Epstein-Barr virus was absent, and API2-MALT1 gene fusion, a recently reported MALT lymphoma-specific gene abnormality, was not detected in any case. Although one patient died of disease 85 months after the diagnosis, other patients were alive with overall 3-year and 5-year survival rates being 89% and 83%, respectively. Among the 22 patients reported previously and in the present series, at least 17 patients (77%) were Asians. These data indicate that thymic MALT lymphoma may represent a distinct subgroup of MALT lymphoma characterized by apparent predilection for Asians, a strong association with autoimmune disease, frequent presence of cysts, consistent plasma cell differentiation, tumor cells expressing IgA phenotype, and consistent lack of API2-MALT1 gene fusion.

Adult↗

PubMed2006

Long hydrocarbon chains serve as unique molecular features recognized by ventral glomeruli of the rat olfactory bulb.

In an effort to understand mammalian olfactory processing, we have been describing the responses to systematically different odorants in the glomerular layer of the main olfactory bulb of rats. To understand the processing of pure hydrocarbon structures in this system, we used the [(14)C]2-deoxyglucose method to determine glomerular responses to a homologous series of alkanes (from six to 16 carbons) that are straight-chained hydrocarbons without functional groups. We found two rostral regions of activity evoked by these odorants, one lateral and one medial, that were observed to shift ventrally with increasing alkane carbon chain length. Furthermore, we successfully predicted that the longest alkanes with carbon chain length greater than our previous odorant selections would stimulate extremely ventral glomerular regions where no activation had been observed with the hundreds of odorants that we had previously studied. Overlaps in response profiles were observed in the patterns evoked by alkanes and by other aliphatic odorants of corresponding carbon chain length despite possessing different oxygen-containing functional groups, which demonstrated that hydrocarbon chains could serve as molecular features in the combinatorial coding of odorant information. We found a close and predictable relationship among the molecular properties of odorants, their induced neural activity, and their perceptual similarities.

Alkanes↗

PubMed2004

Characterization of molecular features, antigen-binding, and in vitro properties of IgG and IgM variants of 4E10, an anti-HIV type 1 neutralizing monoclonal antibody.

The human monoclonal antibody 4E10 has been generated previously by immortalization of peripheral blood cells from an HIV-1-infected individual. This antibody binds to the linear epitope NWFDIT on gp41 and exhibits exceptional neutralizing activity against a broad spectrum of primary HIV-1 isolates. In the present study, molecular features, immunoreactivity, and functional activity of 4E10 were studied. The original hybridoma-derived 4E10 was of subtype IgG(3). Analysis of the variable segment of the heavy chain (VH) demonstrated extensive somatic mutations compared to the closest homologous germline gene VH1-69. Most amino acid substitutions occurred in the complementarity-determining region (CDR) 2, characteristic for an antigen-driven somatic maturation. The heavy chain of the CDR3 (H3) is of unusual length and cannot be attributed with certainty to any specific D(H) locus. To enable mass production and to prolong the in vivo half-life, 4E10 was subsequently cloned as IgG(1) in Chinese hamster ovary (CHO) cells. In additional studies, 4E10 was class switched to the IgM isotype. Binding to the linear epitope NWFDIT was not significantly changed after the cloning procedures. However, in vitro studies revealed dramatic differences in the neutralizing potential. The antiviral activity could be greatly enhanced by change of IgG(3) to IgG(1). In contrast, the IgM isotype almost completely lost its neutralizing potential.

Amino Acid Sequence↗

PubMed1995

The structure of Ascaris hemoglobin domain I at 2.2 A resolution: molecular features of oxygen avidity.

The perienteric hemoglobin of the parasitic nematode Ascaris has an exceptionally high affinity for oxygen. It is an octameric protein containing two similar heme-binding domains per subunit, but recombinant constructs expressing a single, monomeric heme-binding domain (domain 1; D1) retain full oxygen avidity. We have solved the crystal structure of D1 at 2.2 A resolution. Analysis of the structure reveals a characteristic globin fold and illuminates molecular features involved in oxygen avidity of Ascaris perienteric hemoglobin. A strong hydrogen bond between tyrosine at position 10 in the B helix (tyrosine-B10) and the distal oxygen of the ligand, combined with a weak hydrogen bond between glutamine-E7 and the proximal oxygen, grips the ligand in the binding pocket. A third hydrogen bond between these two amino acids appears to stabilize the structure. The B helix of D1 is displaced laterally by 2.5 A when compared with sperm whale myoglobin. This shifts the tyrosine-B10 hydroxyl far enough from liganded oxygen to form a strong hydrogen bond without steric hindrance. Changes in the F helix compared with myoglobin contribute to a tilted heme that may also be important for oxygen affinity.

Amino Acid Sequence↗

PubMed2001

Two novel CNRs from the CNR gene cluster have molecular features distinct from those of CNR1 to 8.

Cadherin-related neuronal receptor (CNR) family proteins are known as synaptic cadherins and Reelin receptors. Here we have identified two novel mouse CNR genes, CNRc1 and CNRc2, orthologues of human protocadherin (Pcdh) alpha-c1 and Pcdhalpha-c2, respectively. While the variable large exons of CNRc1 and c2 contain six conserved extracellular cadherin repeats (EC1-6) and are linked to the constant exons, both contain several molecular features distinct from CNR1-8. CNRc1 and c2 lack the Arg-Gly-Asp (RGD) sequence that is conserved in the EC1 of CNR1-8, which is necessary for binding to Reelin. The present studies confirm that CNRc1 and c2 failed to immunoprecipitate with Reelin. In addition, the regulation of novel CNR expression patterns during brain development is slightly different from that of CNR1. The identification of these new CNR genes characterized by their distinct extracellular function and expression is indicative of the novel diversity of the processes of brain structuring and synapse regulation.

Alternative Splicing↗

PubMed2005

[Acute monocytic leukemia after orthotopic liver transplantation: clinical features, molecular genetics, and significance thereof].

OBJECTIVE: To study the clinical features and molecular genetics of acute monocytic leukemia (AML) after orthotopic liver transplantation and significance thereof. METHODS: The clinical manifestations, laboratory findings, development, diagnosis, treatment, and prognosis of the first case of AML after orthotopic liver transplantation in the world, a Chinese, male, aged 46, were observed. RT-PCR was used to analyze the mRNA expression of FLT3, Pim-1, and Hsp-70 in the bone marrow mononuclear cells (BMMCs) of the patient. Nucleotide sequence analysis was used to detect the mutation of FLT3-ITD. Flow cytometry was used to examine the protein expression of C-kit, a stem cell factor receptor, and platelet derived growth factor receptor-alpha (PDGFRalpha). RESULTS: (1) Three months after the orthotopic liver transplantation the patient manifested symptoms and signs of anemia and thrombocytopenia. Laboratory tests found increase of white blood cells and myeloblasts with Auer's rods. Cytogenetic analysis showed a genotype of 46XY/47XY with an extra chromosome 8. Bone marrow examination revealed increased promonocytes. The diagnosis of chronic myelomonocytic leukemia was made. Five months after the liver transplantation the disease developed to AML. The patient underwent combined chemotherapy (HA or DA regimens) for 5 courses and showed a partial remission both hematologically and in bone marrow examination at first, however, became resistant to all chemotherapeutic agents. RT-PCR showed absence of wild type FLT3 allele. At last the patient died of infection. (2) A FLT3-ITD mutation of "insertion" type was identified in the BMMCs. The Pim-1 mRNA was weakly expressed and the expression of Hsp-70 mRNA was upregulated in the BMMCs. (3) The protein expression of C-kit and that of PDGFRalpha were both upregulated in the BMMCs as showed by flow cytometry. CONCLUSION: Orthotopic liver transplantation may be complicated with acute leukemia heterogeneous in clinical features and hematology. Certain defects in cytogenetics/molecular genetics may attribute to unfavorable prognosis.

HSP70 Heat-Shock Proteins↗

PubMed1988

Nucleotide sequence analysis of cDNA encoding the coat protein of cucumber mosaic virus: genome organization and molecular features of the protein.

The cDNA sequence coding for the coat protein of cucumber mosaic virus (Japanese Y strain) was cloned, and its nucleotide sequence was determined. The sequence contains an open reading frame that encodes the coat protein composed of 218 amino acids. The nucleotide and deduced amino acid sequences of the coat protein of this strain were compared with those of the Q strain; the homologies of the sequences were 78% and 81%, respectively. Further study of the sequences gave an insight into the genome organization and the molecular features of the coat protein. The coding region can be divided into three characteristic regions. The N-terminal region has conserved features in the positively charged structure, the hydropathy pattern and the predicted secondary structure, although the amino acid sequence is varied mainly due to frameshift mutations. It is noteworthy that the positions of arginine residues in this region are highly conserved. Both the nucleotide and amino acid sequences of the central region are well conserved. The amino acid sequence of the C-terminal region is not conserved, because of frameshift mutations, however, the total number of amino acids is conserved. The nucleotide sequence of the 3'-noncoding region is divergent, but it could form a tRNA-like structure similar to those reported for other viruses. Detailed investigation suggests that the Y and Q strains are evolutionarily distant.

Amino Acid Sequence↗

PubMed2003

Colorectal carcinoma: diagnostic, prognostic, and molecular features.

Surgical resection is the primary treatment modality for colorectal cancer, and the pathologic assessment of the resection specimen provides data that is essential for patient management, including the estimation of postoperative outcome and the rationale for adjuvant therapy. The essential elements of the pathological assessment of colorectal cancer resection specimens include the pathologic determination of TNM stage, tumor type, histologic grade, status of resection margins, and vascular invasion. The prognostic and/or predictive value of these elements, as well as guidelines for their derivation and interpretation, are reviewed in detail. Other tissue-based prognostic factors that are strongly suggested by existing data to have stage-independent prognostic value or to predict response to adjuvant therapy but that have not yet been validated for routine patient care are also reviewed. These include perineural invasion, tumor border configuration, host immune response to tumor, and molecular features such as microsatellite instability or loss of heterozygosity of chromosome 18. The need for high-quality, reproducible pathologic data in the care of the colorectal cancer patient, and the dependence of that data on standardization of all aspects of pathological assessment, is emphasized.

Biomarkers, Tumor↗

PubMed2006

Listeria monocytogenes serotype 4b strains belonging to lineages I and III possess distinct molecular features.

A collection of Listeria monocytogenes serotype 4b strains belonging to lineages I and III were examined by PCR and Southern blot analysis using species-, virulence-, and serotype-specific primers and probes. Whereas four serotype 4b lineage I strains reacted in PCR with the serotype 4b-, 4d-, and 4e-specific ORF2110 and virulence-specific lmo1134 and lmo2821 primers, all nine serotype 4b lineage III strains were negative by ORF2110 and lmo1134 primers. In addition, the nine serotype 4b lineage III strains formed two separate groups through their reactions in PCR with virulence-specific lmo2821 primers. Southern blot analysis using species-specific lmo0733 and virulence-specific lmo2821 gene probes largely confirmed the PCR results. These findings indicate that L. monocytogenes serotype 4b strains belonging to lineages I and III possess distinct molecular features.

Animals↗

PubMed2005

[Clinical, genetic and molecular features in 45 patients with Prader-Willi syndrome].

BACKGROUND: Prader-Willi syndrome (PWS) is a neurogenetic disease characterized by neonatal hypotonia, retarded mental and motor development, hypogonadism, hyperphagia, morbid obesity and dysmorphic facial features. It has an incidence of 1:12.000-15.000 newborns and is caused by abnormalities in genes located in 15q11q13. PWS is one of the most frequent genetic disorders and microdeletion syndromes. It is also the most common cause of obesity from genetic origin and it was the first disease in which imprinting and uniparental disomy were recognized as cause of genetic disorders. Seventy to seventy five percent of PWS cases are due to 15q11q13 deletions, 20-25% to uniparental disomy and 1% to mutations in the imprinting center. AIM: To analyze the clinical, genetic and molecular features of patients with PWS, seen at one institution. PATIENTS AND METHODS: Retrospective review of 45 patients (27 males) with PWS seen at the Genetics Outpatient Clinic at INTA. RESULTS: Twenty three (51.1%) patients had a deletion, 13 (28.9%) patients did not have a deletion. In nine patients, fluorescence in situ hybridization (FISH) study was not performed, therefore the presence of deletion was unknown. The clinical score was 8 points for patients younger than 3 years (n=11) and 11.5 points for patients older than 3 years (n=34); for patients aged 12 months or less, the clinical score was 7 points. Mean clinical score was 11 points for patients with deletion and 10 points for patients without deletion. CONCLUSIONS: Most patients with PWS have a deletion; the phenotype depends on age and the clinical score is useful for Chilean patients with PWS.

Adolescent↗

PubMed2003

BCL-2/JH translocation in peripheral blood lymphocytes of unexposed individuals: lack of seasonal variations in frequency and molecular features.

BCL-2/J(H) rearrangement has been proposed as a biomarker for evaluating the genotoxicity of occupational and environmental exposures. Available data on time-related modification of this rearrangement in peripheral blood lymphocytes in unexposed healthy individuals is scarce. We investigated the characteristics of BCL-2/J(H) rearrangements in 33 adults unexposed to genotoxins at 2 seasonal time points: winter and spring. BCL-2/J(H) rearrangement was detected in 79% of individuals (detection limit = 8.48 x 10(-8)). Its frequency ranged from <1 to 40 translocations per million lymphocytes with a significant (p = 0.04) positive correlation with age. No significant modifications of BCL-2/J(H) rearrangement frequency or in the number of clones harboring this rearrangement were observed according the 2 time points. No obvious influence of season-related environmental factors on frequency or molecular features of BCL-2/J(H) rearrangements was found in this population suggesting that this would not be a confounding factor.

Adult↗

PubMed1994

Molecular features, processing and import of the Rieske iron-sulfur protein from potato mitochondria.

The mitochondrial iron-sulfur protein (also termed Rieske iron-sulfur protein) of cytochrome c reductase was purified from potato tubers and identified with heterologous antibodies. The sequences of the N-terminus of this 25 kDa protein and of an internal peptide were determined to design oligonucleotide mixtures for screening a cDNA library. One class of cDNA clones containing an open reading frame of 265 amino acids was isolated. The encoded protein contains the peptide sequences of the 25 kDa protein and shares about 50% sequence identity with the Rieske iron-sulfur proteins from fungi and around 43% with those from mammals. In vitro transcription and translation of the cDNA reveals that the iron-sulfur protein is made as a larger precursor of 30 kDa which is processed by the cytochrome c reductase/processing peptidase complex from potato. The processing product obtained after in vitro processing has the same size as the mature protein imported into isolated mitochondria. The presequence, which targets the protein to the organelle, is 53 amino acids long and has molecular features different from those found in presequences of fungal iron-sulfur proteins, which are processed in two steps. Our results indicate that, unlike in yeast and Neurospora, the presequence of the iron-sulfur protein from potato is removed by a single processing enzyme in one step.

Amino Acid Sequence↗

PubMed1997

Ig VH1 genes expressed in B cell chronic lymphocytic leukemia exhibit distinctive molecular features.

Prior studies revealed that the leukemic B cells of patients with chronic lymphocytic leukemia (CLL) express a restricted Ig heavy chain variable region gene (VH gene) repertoire. However, this restriction needs to be re-evaluated in light of findings that the repertoire of Ig VH genes used by primary B cells of normal adults is actually more restricted than originally assumed. Because of this, we critically examined the Ig VH1 and VH7 genes expressed by leukemia cells of a random panel of patients with B cell CLL (n = 117). Forty-one (35%) had leukemia cells with functional VH1 gene rearrangements. Of these, the large majority expressed Ig VH1-69 (n = 26; 63%). The remaining leukemia cell samples expressed VH1-2 (n = 4; 10%), VH1-3 (n = 2; 5%), VH1-8 (n = 2; 5%), VH1-18 (n = 1; 2%), VH1-45 (n = 1; 2%), and VH1-46 (n = 5; 12%). Only 1 of the 117 examined (<1%) used Ig VH genes of the VH7 subgroup. We found that certain alleles of the IgVH1-69 locus are favored in CLL. Also, leukemia B cells that express VH1-69 have a distinctive use distribution of D and JH gene segments compared with that of VH1-expressing CLL B cells that do not use VH1-69 or non-neoplastic B cells that express VH1-69. Finally, the average length of the heavy chain third complementarity-determining regions (CDR3) of VH1-69-expressing leukemia cells is significantly longer than that of normal adult B cells that also express Ig encoded by VH1-69 genes. Collectively, this study indicates that the Ig expressed in CLL have distinctive molecular features that are not representative of the Ig expressed by primary B cells of normal adults.

Adult↗

PubMed2005

A mouse model recapitulating molecular features of human mesothelioma.

Malignant mesothelioma has been linked to asbestos exposure and generally has a poor prognosis because it is often diagnosed in advanced stages and is refractory to conventional therapy. Human malignant mesotheliomas accumulate multiple somatic genetic alterations, including inactivation of the NF2 and CDKN2A/ARF tumor suppressor genes. To better understand the significance of NF2 inactivation in malignant mesothelioma and identify tumor suppressor gene alterations that cooperate with NF2 loss of function in malignant mesothelioma pathogenesis, we treated Nf2 (+/-) knockout mice with asbestos to induce malignant mesotheliomas. Asbestos-exposed Nf2 (+/-) mice exhibited markedly accelerated malignant mesothelioma tumor formation compared with asbestos-treated wild-type (WT) littermates. Loss of the WT Nf2 allele, leading to biallelic inactivation, was observed in all nine asbestos-induced malignant mesotheliomas from Nf2 (+/-) mice and in 50% of malignant mesotheliomas from asbestos-exposed WT mice. For a detailed comparison with the murine model, DNA analyses were also done on a series of human malignant mesothelioma samples. Remarkably, similar to human malignant mesotheliomas, tumors from Nf2 (+/-) mice showed frequent homologous deletions of the Cdkn2a/Arf locus and adjacent Cdkn2b tumor suppressor gene, as well as reciprocal inactivation of Tp53 in a subset of tumors that retained the Arf locus. As in the human disease counterpart, malignant mesotheliomas from the Nf2 (+/-) mice also showed frequent activation of Akt kinase, which plays a central role in tumorigenesis and therapeutic resistance. Thus, this murine model of environmental carcinogenesis faithfully recapitulates many of the molecular features of human malignant mesothelioma and has significant implications for the further characterization of malignant mesothelioma pathogenesis and preclinical testing of novel therapeutic modalities.

Animals↗

PubMedDate not supplied

Expression of estrogen receptor-alpha and Ki67 in relation to pathological and molecular features in early-onset infiltrating ductal carcinoma.

Estrogen causes breast cancer by triggering proliferation via an estrogen receptor (ER)-mediated mechanism. However, paradoxically, ER alpha, one of the two known ER subtypes, and the proliferation marker, Ki67, are not usually expressed in the same breast tumor. To explore whether ER alpha-positive tumors and proliferating (Ki67-positive) tumors have different tumorigenic characteristics, we performed an immunohistochemical study on 74 early-onset infiltrating ductal carcinomas of the breast. To test this hypothesis, we examined whether ER alpha-positive and Ki67-positive tumors showed differences in (i) pathological grade, (ii) three indices of tumor grade (tubule formation, nuclear pleomorphism, and mitotic number), and (iii) expression of important proteins implicated in breast tumorigenesis (cyclin D1, ErbB2, ATM, BRCA1, Rb, p53, and p21). The results of the multigenic analysis showed that ER alpha and Ki67 were the only two important markers significantly and independently associated with tumor grade, consistent with the above hypothesis. ER alpha-positive, Ki67-negative tumors frequently displayed a low tumor grade (i.e. being well differentiated), whereas Ki67-positive, ER alpha-negative tumors were more likely to exhibit a high tumor grade. In addition, positive ER alpha expression (46 of 74 cases, 62%) correlated well with positive cyclin D1 expression (p < 0.005), less nuclear pleomorphism (p < 0.001), and a low mitotic count (p < 0.005), whereas positive Ki67 expression (36 of 74 cases, 49%) correlated with reduced BRCA1 expression (p < 0.01) and high mitotic activity (p < 0.01). These findings suggest that the expressions of ER alpha and Ki67 might be involved in distinct pathological and molecular features during breast cancer development.

Age of Onset↗

PubMed2002

Histological, immunological and molecular features of a nasal mucosa primary melanoma associated with nasal melanosis.

Nasal mucosa melanoma is a rare entity that may occur together with nasal melanosis. The histological and immunological features and loss of heterozygosity analysis of such lesions have not been reported to date. In the study presented here short-term cell cultures were established from the patient's melanoma and subsequent relapses. Histology, immunohistochemistry, reverse transcription-polymerase chain reaction enzyme-linked immunosorbent assay, human leukocyte antigen analysis, microdissection with subsequent polymerase chain reaction for analysis of loss of heterozygosity were used to characterize the tumour and other cells. Melanoma of the nasal cavity was found, with a surrounding proliferation of atypical melanocytes corresponding to nasal melanosis. Immunoreactivity was found for S-100, gp100, tyrosinase and MelanA protein. Loss of heterozygosity for a p16-flanking marker was found in the tumour and the melanotic cells. Short-term cell cultures expressed tyrosinase and MUC18 at the mRNA level and intercellular adhesion molecule-1 (ICAM-1) and interleukin-12 receptor at the protein level. This is the first time short-term cell cultures have been established and analysed from such a tumour. Melanoma-associated antigens were identified within the tumour. The melanoma and the melanotic cells showed loss of heterozygosity for the p16 gene, which is implicated in melanoma development. This points to a common origin in tumorigenesis. Pathways of tumour escape, such as expression of CD54 and interleukin-10, were observed. The clinical, immunological and molecular features suggest that nasal melanosis should be followed closely.

Adult↗

PubMed2005

Morphological and molecular features of the mammalian olfactory sensory neuron axons: What makes these axons so special?

The main organization and gross morphology of the mammalian olfactory primary pathway, from the olfactory epithelium to the olfactory bulb, has been initially characterized using classical anatomical and ultrastructural approaches. During the last fifteen years, essentially thanks to the cloning of the odorant receptor genes, and to the characterization of a number of molecules expressed by the olfactory sensory neuron axons and their environment, significant new insights have been gained into the understanding of the development and adult functioning of this system. In the course of these genetic, biochemical and neuroanatomical studies, however, several molecular and structural features were uncovered that appear somehow to be unique to these axons. For example, these axons express odorant receptors in their terminal segment, and transport several mRNA species and at least two transcription factors. In the present paper, we review these unusual structural and molecular features and speculate about their possible functions in the development and maintenance of the olfactory system.

Animals↗