Melosis in holocentric chromosomes: Kinetic activity is randomly restricted to the chromatid ends of sex univalents inGraphosoma italicum (Heteroptera)

We have determined the number and location of the nucleolar organizing regions in spermatocytes ofGraphosoma italicum (2n=12A+ XY/XX) by means of silver impregnation, chromomycin A₃/distamycin A staining and fluorescencein situ hybridization. The identification of only one nucleolar organizing region located at one of the X chromosome ends has provided a suitable cytological marker to analyse the segregation of this univalent and that of the XY pseudobivalent during the first and second meiotic divisions respectively. Our results clearly show that at first meiotic metaphase the chromatids of the X chromosome are orientated with their long axes perpendicular to the polar axis. Although the kinetic activity is restricted to only one end in both X chromatids during the first meiotic division, both ends of the same chromatid have the same probability of showing such kinetic activity. In this sense, we also report that the chromatid segregation maybe initiated either at the same sister chromatid ends or at opposite ends in each chromatid. Thus, this indicates a sex chromatid independence as regards to the chromatid segregation during the first meiotic division. Throughout the second meiotic division both ends of the X chromatid are involved with the same probability in the end-to-end association to conform the XY pseudobivalent. This also implies a random localization of the kinetic activity at the ends opposite to those involved in the end-to-end association.accepted for publication by J. S. (Pat) Heslop-Harrison     

Ultrasonographic aspects of urinary schistosomiasis in children of the Dogon plateau and the Niger office; impact of praziquantel treatment

Urinary bilharziasis is a parasitic infection responsible for vesical, urethral and renal lesions. The authors demonstrate the importance of ambulatory echography on a large scale and describe various echographic lesions. Vesical attacks occurred in 27% of the wall irregularity, 44% of the masses and polyps. Pyelic and urethral abnormalities occurred in 16.6% and 29.9% of cases respectively at the baseline in 1991. These prevalence rates decreased after seven years, in 1998. The authors discuss the utility of chemotherapy with praziquantel and the necessity of a periodical mass treatment in the areas with high bilharziasis endemicity in Mali.     

Establishment and characterization of a continuous human chondrosarcoma cell line,ch-2879: comparative histologic and genetic studies with its tumor of origin

Chondrosarcomas are malignant cartilage-forming tumors that represent the second most common malignant solid tumor of bone. These biologically poorly understood neoplasms vary considerably in clinical presentation and biologic behavior. Chemotherapy and radiation therapy are generally ineffective. Here we describe the establishment and characterization of a new human chondrosarcoma cell line named ch-2879, and we compare the cell line with its tumor of origin. The cell line was established from a recurrent grade 3 chondrosarcoma of the chest wall and characterized by growth kinetics and morphologic studies. Immunocytochemistry and RT-PCR were performed to examine the expression of cartilage-specific phenotypes. Genetic characterization was performed using cytogenetics, fluorescence in situ hybridization, flow cytometry, and molecular techniques for analysis of the genes implicated in cell cycle control, amplification of MDM2, CDK4, and Cyclin D1, and mutations in the p53 gene. ch-2879 cells were subcultured for more than 80 passages. They expressed vimentin, HNK-1, HBA-71, Ki-67, cyclin D1, Fli-1, S-100, p21, p27, and p53 and were negative for cytokeratin, EMA, p14, p16, MDM2, Rb, and c-erb-b2 antigens. Cytogenetically the recurrent tumor showed a hyperhaploid karyotype with clonal numerical and structural abnormalities. The sole structural abnormality was a chromosome derivative of a t(1;21) translocation. The cell line at passage 3 showed two populations: the hyperhaploid and an exactly duplicated, hypotriploid population. After the 18th passage, only the hypotriploid population was present. The cells expressed collagen 2. Molecular comparison of the primary and recurrent tumor evidenced an in vivo molecular change consisting of a deletion of 9p21 genes in the recurrence, probably caused by a selection process. Because of its gene expression profile, including expression of genes implicated in chondrogenesis in uncoated plastic dishes, this cell line may prove useful for cellular and molecular studies as well as studies of chondrosarcoma characterization and treatment.     

Acidic pH and increasing [Ca(2+)] reduce the swelling of mucins in primary cultures of human cervical cells

BACKGROUND: Cervical mucus is a heterogeneous mixture of water, ions and mucins that form a hydrophilic polymer gel. Mucins, the main components of mucus, are condensed inside secretory granules and swell to become a hydrogel after exocytosis. Using human cervical secretory cell primary cultures, the effect of [Ca(2+)] and [H(+)] on the swelling velocity of mucin granules was investigated in vitro. METHODS and RESULTS: Immunocytochemistry demonstrated that estrogen and progesterone receptors were expressed in cultured secretory cells along with mucins type 1, 4, 5AC and 5B. Exocytosis of secretory cells, recorded by videomicroscopy, showed that during swelling, the radius of the secretory granule matrix followed first-order kinetics. An increase in extracellular [Ca(2+)] from 1 to 4 mmol/l or a reduction in pH from 7.4 to 6.5 was seen to produce a significant decrease in the velocity of swelling of the secretory granule matrix. CONCLUSIONS: The inverse relationship observed between the diffusion of the granular matrix and the extracellular [Ca(2+)] or [H(+)] suggested that changes in cation concentration might drastically affect the swelling characteristics of mucins and provide a control mechanism for the observed viscoelastic properties of mucus.     

A functional survey of the enhancer activity of conserved non-coding sequences from vertebrate Iroquois cluster gene deserts

Recent studies of the genome architecture of vertebrates have uncovered two unforeseen aspects of its organization. First, large regions of the genome, called gene deserts, are devoid of protein-coding sequences and have no obvious biological role. Second, comparative genomics has highlighted the existence of an array of highly conserved non-coding regions (HCNRs) in all vertebrates. Most surprisingly, these structural features are strongly associated with genes that have essential functions during development. Among these, the vertebrate Iroquois (Irx) genes stand out on both fronts. Mammalian Irx genes are organized in two clusters (IrxA and IrxB) that span >1 Mb each with no other genes interspersed. Additionally, a large number of HCNRs exist within Irx clusters. We have systematically examined the enhancer activity of HCNRs from the IrxB cluster using transgenic Xenopus and zebrafish embryos. Most of these HCNRs are active in subdomains of endogenous Irx expression, and some are candidates to contain shared enhancers of neighboring genes, which could explain the evolutionary conservation of Irx clusters. Furthermore, HCNRs present in tetrapod IrxB but not in fish may be responsible for novel Irx expression domains that appeared after their divergence. Finally, we have performed a more detailed analysis on two IrxB ultraconserved non-coding regions (UCRs) duplicated in IrxA clusters in similar relative positions. These four regions share a core region highly conserved among all of them and drive expression in similar domains. However, inter-species conserved sequences surrounding the core, specific for each of these UCRs, are able to modulate their expression.     

Characterization of a reduced peptide bond analogue of a promiscuous CD4 T cell epitope derived from the Plasmodium falciparum malaria vaccine candidate merozoite surface protein 1

Use of synthetic peptides as vaccine components is hampered by their susceptibility to enzymatic degradation and rapid clearance from biological fluids. Introduction of non-natural structural modifications can render peptides more resistant to enzymatic degradation, encouraging attempts to profile such non-natural ligands as components of synthetic sub-unit vaccines. We have compared the antigenic and immunogenic properties of a series of non-natural peptide analogues derived from a promiscuous T cell epitope of the major Plasmodium falciparum malaria vaccine candidate merozoite surface protein 1 (MSP-1). A series of HLA class II restricted MSP-1(38-58)-specific TCC established from three volunteers were characterized for their minimal epitope and fine specificity. T cell stimulatory activities of a series of pseudo-peptide analogues with single reduced peptide bond Psi-[CH2-NH] modifications were compared with those of single d-amino acid replacement analogues. Compared to reduced peptide bond analogues the single d-amino acid replacement analogues turned out to be less suitable for stimulation of TCC. In particular, the reduced peptide analogue carrying a Psi-[CH2-NH] backbone modification between positions V52 and L53 of MSP-1(38-58) demonstrated properties that would make it a more suitable vaccine component than the unmodified parent peptide. First, the pseudo-peptide stimulated a number of TCC restricted by a range of HLA class II alleles. Second, trypsin treatment in combination with T cell stimulation assays provided evidence for increased resistance to proteolytic digestion. Third, the parasite-binding anti-MSP-1 mAb 7.27 recognized best this particular pseudo-peptide in competition ELISA experiments and its immunogenicity in out-bred Aotus monkeys was superior to that of the parent peptide eliciting antibodies cross-reactive with native MSP-1.     

A self-setting single-component calcium phosphate cement

Following an original synthesis route, we have prepared a single-component calcium phosphate apatite-like powder which settles and hardens when mixed with deionized water in an approximative 1.2 g:1 ml ratio. This paper describes the first physico-chemical studies and characterizations of the material. Observations of its in vitro behavior show a slight volume contraction and toxicity against fibroblasts bone marrow cells on disks of compacted powder. It is suggested that after an improvement of the powder characters such as grain size, and the choice of another hardening liquid, to name a few, this material should be a potential--or an ingredient of--bone cement.