Anticentromere antibody induced by immunization with centromere protein a and Freund's complete adjuvant may interfere with mouse oocyte meiosis

BACKGROUND

Anticentromere antibody (ACA) is a member of the antinuclear antibody (ANA) family, and recent studies have found that ACA may be associated with oocyte maturation disorders; however, the possible mechanism behind this phenomenon remains unknown. We conducted this study to investigate whether ACA could penetrate into the living oocytes and interfere with oocyte meiosis in a mouse model.

METHODS

We divided mice into three groups: human recombinant centromere protein-A (human CENP-A, HA) and complete Freund's adjuvant (CFA) were used to immunize mice for the study group (HA + CFA), and mice injected with CFA (CFA group) or saline (Saline group), respectively, served as controls. After immunization, serum anti-CENP-A antibody was detected by indirect immunofluorescence assay (IIFT) and enzyme-linked immunosorbent assay (ELISA). Chromosome alignment and intracellular IgG localization in MI- and MII-stage oocytes were investigated by immunofluorescence analysis.

RESULTS

Positive ACAs were successfully induced by immunization with CENP-A and CFA, and results showed that the serum level of anti-CENP-A antibody was significantly higher in the HA + CFA group compared with the control groups. There was marked increase of chromosome misalignments in MI and MII oocytes in the HA + CFA group compared to the control groups. However, no oocytes from any of the three groups showed intracellular antibody immunofluorescence.

CONCLUSIONS

The development and maturation of oocytes were impaired in peripheral ACA positive mice, which exhibited severe chromosomal misalignments in metaphase meiosis; however, no evidence of ACAs entering the oocytes was observed, thus the underlying mechanism needs further exploration.

Effects of tumor necrosis factor-alpha on porcine oocyte meiosis progression, spindle organization, and chromosome alignment

OBJECTIVE

To evaluate the effects of tumor necrosis factor-alpha (TNF-alpha) on porcine oocyte maturation, spindle dynamics, and chromosome alignment.

DESIGN

Controlled, prospective study.

SETTING

University hospital and IVF research laboratory.

ANIMAL(S)

Ovaries collected from slaughtered prepubertal gilts.

MAIN OUTCOME MEASURE(S)

Oocyte maturation rate and cytoskeleton distribution. MATERIALS AND METHOD(S): Immature porcine oocytes (GV) were exposed to TNF-alpha at a concentration of 0 (as a control), 1, 5, 10, 100, 200, or 600 ng/mL in M199 medium. Oocytes were cultured for 24 hours to the pre-MI stage or 44 hours to the MII stage. After in vitro maturation for 44 hours, the rates of GV oocytes reaching MII stage were assessed, and MII oocytes were fixed for further examination of the cytoskeleton and the chromosomal distribution.

RESULT(S)

The TNF-alpha concentration at 5 ng/mL decreased the porcine oocyte maturation rate compared with the control after culture for 44 hours, whereas exposure to 10 or 100 ng/mL TNF-alpha resulted in a significant increase in the frequency of defective spindles or abnormal microfilament distribution. Exposed to 200 ng/mL, TNF-alpha caused a significantly higher abnormality rate of chromosome alignment when compared with the controls.

CONCLUSION(S)

Exposure of porcine oocytes to an elevated TNF-alpha concentration clearly caused a reduction in their maturation from GV stage to MII stage and increased the proportion of oocytes with abnormal chromosome alignment and cytoskeleton structure.

[The protective effect of molsidomin in immune ovarian pathology in mice]

Experimental immune ovarian failure in CBA mice was induced by either administration of xenogenic anti-ovarian antibodies (scheme 1) or immunization with allogenic ovarian extracts (scheme 2). It was shown that both types of treatment impaired the meiotic maturation of oocytes: the number of cells at the stages of metaphase I and metaphase II decreased compared to the cells of control mice. In both schemes of experiments, impaired oogenesis was accompanied by reduction of percentage of viable follicular cells and by increase in the part of cells possessing morphological features of apoptosis. In contrast, the number of necrotic follicular cells increased in scheme 2 only. The donor of nitric oxide molsidomin (10 mg/ kg), when injected an hour before administration of xenogenic anti-ovarian antibodies or allogenic ovary extracts, improved the meiotic maturation of oocytes and favored follicular, lymph nodes and thymus cells survival by decreasing the number of apoptotic and necrotic cells.

[Death of the ovarian follicular cells in mice with impaired oogenesis of the immune nature]

An impairment of the meiotic maturation of the oocytes has been shown in vitro for 2 types of immune damage of the ovaries in mice induced by xenogenic antiovarial antibodies and immunization with allogenic ovaria. Impairment of the oogenesis was followed by the follicular cell death, primarily by on the apoptic way, but under the immunization with allogenic ovary a necrotic way of their death was also activated.

Identification of CT46/HORMAD1, an immunogenic cancer/testis antigen encoding a putative meiosis-related protein

Transcripts with ESTs derived exclusively or predominantly from testis, and not from other normal tissues, are likely to be products of genes with testis-restricted expression, and are thus potential cancer/testis (CT) antigen genes. A list of 371 genes with such characteristics was compiled by analyzing publicly available EST databases. RT-PCR analysis of normal and tumor tissues was performed to validate an initial selection of 20 of these genes. Several new CT and CT-like genes were identified. One of these, CT46/HORMAD1, is expressed strongly in testis and weakly in placenta; the highest level of expression in other tissues is <1% of testicular expression. The CT46/HORMAD1 gene was expressed in 31% (34/109) of the carcinomas examined, with 11% (12/109) showing expression levels >10% of the testicular level of expression. CT46/HORMAD1 is a single-copy gene on chromosome 1q21.3, encoding a putative protein of 394 aa. Conserved protein domain analysis identified a HORMA domain involved in chromatin binding. The CT46/HORMAD1 protein was found to be homologous to the prototype HORMA domain-containing protein, Hop1, a yeast meiosis-specific protein, as well as to asy1, a meiotic synaptic mutant protein in Arabidopsis thaliana.

The targeting of somatic hypermutation closely resembles that of meiotic mutation

We have compared the microsequence specificity of mutations introduced during somatic hypermutation (SH) and those introduced meiotically during neutral evolution. We have minimized the effects of selection by studying nonproductive (hence unselected) Ig V region genes for somatic mutations and processed pseudogenes for meiotic mutations. We find that the two sets of patterns are very similar: the mutabilities of nucleotide triplets are positively correlated between the somatic and meiotic sets. The major differences that do exist fall into three distinct categories: 1) The mutability is sharply higher at CG dinucleotides under meiotic but not somatic mutation. 2) The complementary triplets AGC and GCT are much more mutable under somatic than under meiotic mutation. 3) Triplets of the form WAN (W = T or A) are uniformly more mutable under somatic than under meiotic mutation. Nevertheless, the relative mutabilities both within this set and within the SAN (S = G or C) triplets are highly correlated with those under meiotic mutation. We also find that the somatic triplet specificity is strongly symmetric under strand exchange for A/T triplets as well as for G/C triplets in spite of the strong predominance of A over T mutations. Thus, we suggest that somatic mutation has at least two distinct components: one that specifically targets AGC/GCT triplets and another that acts as true catalysis of meiotic mutation.

A putative susceptibility locus on chromosome 18 is not a major contributor to human selective IgA deficiency: evidence from meiotic mapping of 83 multiple-case families

Previous reports of an association between constitutional chromosome 18 abnormalities and low levels of IgA suggested that this chromosome contains a susceptibility locus for selective IgA deficiency (IgAD), the most frequent Ig deficiency in humans. IgAD is genetically related to common variable immunodeficiency (CVID), characterized by a lack of additional isotypes. Our previous linkage analysis of 83 multiple-case IgAD/CVID families containing 449 informative pedigree members showed a significantly increased allele sharing in the chromosome region 6p21 consistent with allelic associations in family-based and case-control studies and provided the evidence for a predisposing locus, termed IGAD1, in the proximal part of the MHC. We have typed the same family material at 17 chromosome 18 marker loci with the average intermarker distance of 7 cM. A total of 7633 genotypes were analyzed in a nonparametric linkage analysis, but none of the marker loci exhibited a significantly increased allele sharing in affected family members. In addition, reverse painting and deletion mapping of a panel of constitutional chromosome 18 deletions/translocations showed the presence of IgA-deficient and IgA-proficient patients with the same abnormality and did not reveal a region commonly deleted. The linkage analysis of chromosome 8 and 21 regions involved in reciprocal translocations t(8;18) and t(18;21), which were identified in two patients lacking IgA, did not disclose a significant allele sharing. Although these results do not exclude the presence of a minor predisposing locus on this chromosome, such a putative locus would confer a population risk of developing IgAD/CVID much lower than IGAD1.

Characterization of human gamma 4 switch region polymorphisms suggests a meiotic recombinational hot spot within the Ig locus: influence of S region length on IgG4 production

Human gamma4 gene RFLPs, revealed after BamHI digestion, show IGHG4 alleles of 9.0 (9.2), 9.4, and 9.6 kb at various frequencies in different ethnic populations. Studies in immunodeficient individuals have previously suggested that the 9.4 BamHI allele is associated with a higher serum level of IgG4 than the 9.0 (9.2) BamHI allele, but it is not clear whether this is associated with the S region itself or other control elements. In addition, a duplication of the 9.4-kb gamma4 allele has recently been observed in a high proportion of normal donors. We therefore undertook a study of the structural basis for the difference in Ab levels in the various gamma4 alleles. We demonstrate that the Sgamma4 alleles differ in length due to deletions and insertions of a varying number of 79-bp Sgamma4 repeat units. Two novel RFLPs, 8.8 and 9.1 kb, were also observed. The alleles are likely to be generated by unequal crossing over, and the breakpoints cluster in Sgamma4 repeat units that contain chi-like motifs, implicating chi-like sequences in the meiotic recombination. Our data support the idea that the 9.4-kb BamHI allele is more productive than the 9.0 (9.2)-kb allele in normal healthy donors, possibly due to the extended switch regions, whereas duplication of the gamma4 gene has no effect on switching and IgG4 serum levels.

PUMA1: a novel protein that associates with the centrosomes, spindle and centromeres in the nematode Parascaris

We have identified a 227 kDa spindle- and centromere-associated protein in Parascaris, designated PUMA1 (Parascaris univalens mitotic apparatus), using a monoclonal antibody (mAb403) generated against Parascaris embryonic extracts. PUMA1 distribution was studied by immunofluorescence microscopy in mitotic and meiotic Parascaris cells, where centromere organization differs greatly. In mitosis, PUMA1 associates throughout cell division with the centrosomes and kinetochore-microtubules, and it concentrates at the continuous centromere region of the holocentric chromosomes. PUMA1 also localizes to the spindle mid-zone region during anaphase and at the midbody during telophase. In meiosis, PUMA1 associates with the centrosomes and with the discrete centromeric regions lacking kinetochore structures. The analysis of colchicine-treated embryos indicated that the association of PUMA1 with the centromeric region depends on microtubule integrity. mAb403 also recognizes spindle components in Drosophila. A series of overlapping cDNAs encoding the gene were isolated from a Parascaris embryonic expression library. Analysis of the nucleotide sequence identified an open reading frame capable of encoding a protein of 227 kDa. Analysis of the protein sequence indicated that PUMA1 is predicted to be a coiled-coil protein containing a large central alpha-helical domain flanked by nonhelical terminal domains. The structural features and cellular distribution of PUMA1 suggest that it may play a role in the organization of the spindle apparatus and in its interaction with the centromere in Parascaris.

Non-random fertilization in mice correlates with the MHC and something else

One evolutionary explanation for the success of sexual reproduction assumes that sex is an advantage in the coevolutionary arms race between pathogens and hosts. Accordingly, an important criterion in mate choice and maternal selection thereafter could be the allelic specificity at polymorphic loci involved in parasite-host interactions, e.g. the MHC (major histocompatibility complex). The MHC has been found to influence mate choice and selective abortions in mice and humans. However, it could also influence the fertilization process itself, i.e. (i) the oocyte's choice for the fertilizing sperm, and (ii) the outcome of the second meiotic division after the sperm has entered the egg. We tested both hypotheses in an in vitro fertilization experiment with two inbred mouse strains congenic for their MHC. The genotypes of the resulting blastocysts were determined by polymerase chain reaction. We found nonrandom MHC combinations in the blastocysts which may result from both possible choice mechanisms. The outcome changed significantly over time, indicating that a choice for MHC combinations during fertilization may be influenced by one or several external factors.

A novel stage-specific differentiation antigen is expressed on mouse testicular germ cells during early meiotic prophase

A murine cell surface antigen exhibiting stage-specific expression during spermatogenesis was detected with two monoclonal antibodies (mAbs), designated BC7 and CA12. In mouse testis, these mAbs recognized a small population of cells located near the periphery of seminiferous tubules at stages XII and I-VI, and these spermatogenic cells were identified as zygotene and early pachytene spermatocytes. Expression of the antigens was transient and was not detected in germ cells at more advanced stages of spermatogenesis such as late pachytene spermatocytes and round spermatids. Immunoprecipitation and immunoblotting studies showed that both mAbs CA12 and BC7 reacted with the same antigenic molecule, which had an estimated molecular mass of 95 kDa. CA12/BC7 antigen, detected in plasma membrane fraction, was a glycoprotein with sialic acid residues and had affinity with WGA lectin. Furthermore, intraperitoneal injection of mAb BC7 caused an apparent spermatogenic disturbance in prepubertal mice. These results suggested that CA12/BC7 antigen, a novel cell surface glycoprotein, is an essential molecule that plays an important role during early meiotic prophase of spermatogenesis.

Characterization of male meiotic germ cell-specific antigen (Meg 1) by monoclonal antibody TRA 369 in mice

We have identified a male meiotic germ cell-specific antigen (Meg 1) with monoclonal antibody (mAb) TRA 369 in mice. The Meg 1 antigen was strongly expressed in specific steps of meiotic germ cells from pachytene spermatocyte to early spermatid, and not in other germ cells or somatic cells. Immunohistochemical examination revealed that the antigen was localized to the cytoplasm and was not distributed in the nucleus or on the cell surface. This antigen was demonstrated to have a molecular weight of 93 kDa and an isoelectric point of 5.2 by Western blotting. This molecule was first detected in the testis of 13-day-old mouse when pachytene spermatocytes first appeared. Thus this is a differentiation-specific antigen in male meiotic germ cells, and mAb TRA 369 is a useful tool to study the regulation of germ cell differentiation and to define germ cell development in a molecular level.