In line with our ancestors: Oct-4 and the mammalian germ

The transcription factor Oct-4 is expressed specifically in the totipotent germline cycle of mice. Cells that lose Oct-4 differentiate along different paths to form embryonic and extraembryonic somatic tissue. Oct-4 may maintain the potency of stem and germline cells by preventing all other differentiation pathways. Oct-4 may also regulate the molecular differentiation of cells in the germ lineage as it progresses from the fertilized egg, through cleavage stage/morula blastomeres, blastocyst, inner cell mass, epiblast, germ cells, and gametes. The factors that regulate, and are regulated by, Oct-4 are reviewed with respect to the phenomena of cell potency and germ/soma segregation and differentiation.

Differential expression of the Oct-4 transcription factor during mouse germ cell differentiation

The POU transcription factor Oct-4 is expressed in early mouse embryogenesis and in pluripotent ES and EC stem cell lines. After gastrulation in the embryo, Oct-4 expression is confined to the germline. The present study provides evidence that Oct-4 undergoes downregulation during oogenesis and spermatogenesis, coincident with entry into meiosis. Furthermore, analysis of maturation stages of oocytes showed that Oct-4 is upregulated de novo in the final stages of meiotic prophase I in female germ cells. These data suggest that Oct-4 downregulation in germ cells in both sexes might represent one of the molecular triggers involved in the commitment to meiosis. The upregulation of Oct-4 in oocytes at the completion of the prophase I of meiotic division further suggests a specific involvement of this transcription factor in oocyte growth or the acquisition of meiotic competence.

Identification of a promoter region generating Sry circular transcripts both in germ cells from male adult mice and in male mouse embryonal gonads

The mouse testis determining gene Sry is expressed in somatic cells of the differentiating male gonad as a linear transcript, encoding a transcription factor containing an HMG box. In the adult mouse testis, Sry expression occurs in meiotic and postmeiotic germ cells. The mouse genomic Sry locus is characterized by two arms of a large inverted repeat, flanking a unique region that, between an acceptor and a donor splice site, contains a single exon encoding the Sry protein. In germ cells from the adult mouse testis, Sry RNA is a circular molecule, which is generated by an inverted splicing event that utilizes the above-mentioned splice sites. Thus, a circular exon is spliced out starting from a large linear RNA precursor containing both arms of the inverted repeat, which pair and generate a large stem-loop structure. Using reverse transcription-polymerase chain reaction and an RNase protection assay, we have now mapped the 5' end of this precursor RNA in the 5' arm of the inverted repeat. Gel mobility shift assay and in vitro transcription with nuclear extracts from adult germ cells further confirm that a region immediately 5' upstream of two transcriptional initiation sites of the precursor RNA contains a promoter sequence in which two consensus Sry binding sequences are specifically recognized by nuclear factors present in adult germ cells but not in Sertoli cells. We also show that the linear precursor of the Sry circular transcript and its splicing product are specifically expressed not only in adult germ cells but also in male embryonal gonads between 11.5 and 13.5 days postcoitum, immediately after the expression of the linear transcript starting from the unique region.

The c-kit receptor is involved in the adhesion of mouse primordial germ cells to somatic cells in culture

The receptor encoded by the W (c-kit) locus is expressed on the membrane of mouse primordial germ cells, whereas its ligand termed stem cell factor (SCF), encoded by the Sl locus, is expressed on the membrane of somatic cells associated with both the primordial germ cell migratory pathways and homing sites. Using an in vitro short time assay which allows a quantitative measure of adhesion between cells, in the present paper we show that SCF/c-kit interaction can modulate primordial germ cell adhesion to somatic cells. We report that the adhesiveness of 11.5 dpc primordial germ cells to four types of somatic cells in culture (TM4 cells, STO fibroblasts, bone marrow stromal cells and gonadal somatic cells) is significantly reduced by antibodies directed against c-kit receptor or SCF, as well by soluble SCF. This SCF/c-kit mediated adhesion seems independent of SCF-induced tyrosine autophosphorylation of c-kit receptor. Moreover, primordial germ cells showed a poor ability to adhere to a bone marrow stromal cell line carrying the Sl(d) mutation (unable to synthesize membrane-bound SCF). This adhesiveness was not further impaired by anti-c-kit antibody. These results demonstrate that SCF/c-kit interaction contributes to the adhesion of primordial germ cells to somatic cells in culture and suggest that the role played by SCF in promoting survival, proliferation and migration of these cells in vitro and in vivo, demonstrated by several studies, might depend on the ability of the membrane-bound form of this cytokine to directly mediate primordial germ cell adhesion to the surrounding somatic cells.

Isolation of highly purified type A spermatogonia from prepubertal rat testis

We have developed a new method that allows isolation of highly purified type A spermatogonia from prepubertal rats. The procedure is based on the maximal release of spermatogonia from the seminiferous epithelium obtained by the complete enzymatic digestion of the tubular basal lamina, followed by removal of contaminating somatic cells through adhesion to plastic dishes coated with the lectin Datura stramonium agglutinin and fractionation on a discontinuous Percoll gradient. The cell suspension obtained contains up to 85% type A spermatogonia. Besides morphological criteria, the identification of germ cells and somatic cells has been performed by means of immunocytochemical markers, such as c-kit receptor, which is present only in germ cells, and vimentin, which is present only in somatic cells. All type A spermatogonia isolated were c-kit positive, thus suggesting that c-kit receptor is present in both undifferentiated and differentiating type A spermatogonia. Preliminary culture experiments demonstrate that spermatogonia survival in vitro was significantly improved by the addition of 10% fetal calf serum or horse serum to the culture medium; however, optimal culture conditions remain to be established. In vitro studies on isolated spermatogonia may provide a significant contribution toward elucidation of the mechanisms regulating spermatogonial proliferation and differentiation.

Role of stem cell factor in somatic-germ cell interactions during prenatal oogenesis

During embryogenesis germ cells originate from primordial germ cells (PGCs). The development of mammalian PGCs involves a number of complex events (formation and segregation of PGC precursors, PGC migration and proliferation) which lead to the differentiation of oocytes or prospermatogonia (for a review see De Feliciet al., 1992). During recent years developments in methods for isolation, purification and culture of mouse PGCs have led to significant progress in the understanding of molecular mechanisms of migration, proliferation and differentiation of these cells (for reviews see De Felici, 1994; and De Felici & Pesce, 1994a). In this paper we describe the key role played by stem cell factor (SCF) in PGC development and early folliculogenesis.

Pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates adenylate cyclase and promotes proliferation of mouse primordial germ cells

During migration and for about 2 days after their arrival in the gonadal ridges, primordial germ cells (the embryonic precursors of gametes of the adult animal) proliferate actively. Certain growth factors, such as stem cell factor and leukemia inhibitory factor, seem to be essential for survival, proliferation and possibly differentiation of mouse primordial germ cell in vivo and/or in vitro. Similarly, increase in intracellular cAMP is followed by a marked enhancement of primordial germ cell proliferation, at least in culture. In the present study, we show that pituitary adenylate cyclase-activating polypeptides (PACAP-27 and PACAP-38), two neuropeptides of the secretin-glucagon-vasoactive intestinal polypeptide-GH-releasing hormone family, stimulate in vitro proliferation of mouse primordial germ cells, bind to primordial germ cells and gonadal somatic cells (possibly to type I PACAP receptor) and activate adenylate cyclase in the same cells. Moreover, PACAP-like immunoreactivity was found in gonadal ridges, mostly on germ cell surface. In conclusion, evidence is provided that PGC proliferation can be stimulated by certain bioactive polypeptides, thus suggesting a novel regulatory role for such compounds in early gonad development.

[HCV superinfection in a chronic carrier of HBV]

The paper reports a case of acute hepatitis C (HCV) in a patient who was a chronic carrier of hepatitis B virus (HBV) during the course of which the authors observed a transient HBsAg clearance. The 53-year-old patient was a carrier of chronic HBV infection in an integrated minus variant phase. The patient presented an abrupt increment in aminotransferase (ALT) which was not compatible with the typical "a poussée" progress of atypical chronic HBV hepatitis in that it was associated with HbsAg clearance in the absence of signs of superinfection by delta hepatitis virus (HDV), with subsequent repositivisation of HBsAg and contemporary anti-HCV seroconversion (RIBA positive for C-22, C-33, C-100, 5-1-1) on clinical remission. Polymerase chain reaction (PCR) was negative on remission for both HBV DNA and HCV. RNA became positive six months afterwards for HCV RNA alone; moreover HBsAg, anti-HCV, RIBA C-22, C-33, C-100, 5-1-1 were constantly positive, thus further confirming the inhibitory capacity of HCV towards HBV and not vice versa, as also shown by the chronic nature of infection and deterioration of clinical conditions. The authors conclude by underlining the need to assay for HCV RNA using a PCR method in alla cases of re-acutisation of chronic hepatitis due to both wild virus B and the domestic virus during the course of which HBsAg becomes negative, even transiently, in the absence of Delta superinfection.

Purification of mouse primordial germ cells by MiniMACS magnetic separation system

During migration toward gonadal ridges, primordial germ cells (PGCs; the earliest identifiable germ cells in the embryo) are very few in number, move along different tissues, and are not identifiable by morphological criteria alone. Here we report the use of the magnetic cell sorter MiniMACS as a tool for the isolation of such rare cells from 10.5- to 13.5-days post coitum mouse embryos. Cells stained sequentially by TG-1 (a monoclonal IgM antibody known to bind to the surface of PGCs) and superparamagnetic microbeads coated with secondary anti-mouse IgM antibody were separated on a magnetic column. Unlabeled cells (somatic cells) pass through the column, while labeled cells (germ cells) are retained. The retained cells can be eventually easily eluted and immediately used for biochemical studies or grown in suitable in vitro culture systems.

Immunoaffinity purification of migratory mouse primordial germ cells

Primordial germ cells (PGCs) are the earliest identifiable germ cells in the embryo. It has not previously been possible to purify PGCs from mammalian embryos at early stages of development (before they arrive in the gonads), when such cells are very low in number, are moving along different tissues toward the gonadal ridges, and are not identifiable by morphological criteria alone. We report here that the use of PGC-specific TG-1 antibody in combination with immunoaffinity adhesion to plastic plates coated with anti-mouse IgM secondary antibody allows the isolation of reasonably pure yields of migratory PGCs from 9.5- to 11.5-dpc mouse embryos.

Tax-induced HTLV-I LTR transcriptional activation is modulated by phosphorylation

We studied the effect of protein phosphatase and kinase inhibitors on Tax-mediated transcription of constructs carrying the reporter gene chloramphenicol acetyl transferase under the control of either the full-length LTR of HTLV-I or three copies of the tax-responsive 21-bp repeats. We observed that treatment with okadaic acid, which inhibits the serine/threonine protein phosphatases type 1 and 2A, reduced HTLV-I LTR transcriptional activation in MT2 and K562 cells; on the contrary, the enhancer activity of the 21-bp sequences was significantly increased in both cell lines; treatment with the protein kinase C inhibitor H-7 blocked Tax-mediated transcription of both constructs. We also found that treatment with sodium orthovanadate, a tyrosine phosphatase inhibitor, reduced Tax-mediated activation of both plasmids. These findings indicated that specific serine/threonine phosphorylation events are required for Tax-mediated HTLV-I LTR activation and also suggested that phosphorylation at tyrosine residues is involved in this process.

Chloral hydrate is recombinogenic in the wing spot test in Drosophila melanogaster

In order to characterise the response of the wing spot test in Drosophila melanogaster to the effects of compounds with known aneugenic properties, experiments were performed with chloral hydrate (CH). Following chronic exposure of 72-h-old larvae to rising concentrations of CH, significant increases in the frequency of small (1-2 cells) single spots were observed. Comparison of results obtained in parallel from the wings of marker-trans-heterozygous individuals and individuals heterozygous for one of two different balancer chromosomes suggests that practically all the single clones originated from recombinational events. Twin clone frequencies were, however, only weakly affected. These results are discussed with reference to the literature regarding the effects of CH in different experimental systems and to the characteristics of Drosophila as a tester organism.

Histotypic in vitro reorganization of dissociated cells from mouse fetal gonads

Cell suspensions obtained from the testes of 13.5-14.5 day post coitum (dpc) mouse embryos reaggregate in cord-like structures following in vitro culture for 24 h on a reconstituted basement membrane (Matrigel). Ovarian cells of the same fetal age or cell suspensions from sex indifferent gonadal ridges (11.5 dpc embryos) form an organized cell network but not cord-like structures. Antibodies directed against laminin or against the alpha 6 subunit of its integrin receptor prevent such morphogenetic processes. The addition of 5 micrograms/ml cycloheximide, cytochalasin B or tunicamycin also inhibits the phenomenon. Interestingly, compounds that increase intracellular cyclic AMP (cAMP) (dbcAMP, forskolin and isobutyl-1-methylxanthine) induce embryonic testicular cells to organize into structures similar to those assembled by ovarian or sex indifferent cell suspensions. These findings offer a simple in vitro model for studying some aspects of early gonad development and provide novel experimental evidence that cell motility and cell-cell adhesion, possibly regulated by cAMP dependent mechanisms, are likely to play an important role in gonad morphogenesis.

Apoptosis in mouse primordial germ cells: a study by transmission and scanning electron microscope

A detailed study of the death in vitro of mouse primordial germ cell (PGCs) by means of transmission and scanning electron microscopy is reported. The results show that after 4-5 h of culture 15-20% PGCs assume the typical morphological features of apoptotic cells, including chromatin condensation in dense masses under the nuclear membrane, compaction of the cytoplasm, crowding of organelles and surface protuberances. Cells then break up into discrete fragments (apoptotic bodies) which eventually degenerate by "secondary necrosis". It is possible that apoptosis plays a biologically useful role in avoiding uncontrolled PGC proliferation and in eliminating misplaced germ cells whose survival might be harmful to the animal.

Growth factors in mouse primordial germ cell migration and proliferation

Information obtained mainly from in vitro culture studies and genetic analysis of mouse mutants White spotting and Steel indicate a pivotal role of growth factors in the development of mouse primordial germ cells (PGCs). While stem cell factor (SCF) and TGF beta 1 seem to have a role in PGC migration (as an adhesion factor and a chemoattractant, respectively), the former is certainly required for PGC survival in vitro and probably in vivo as well. Recent findings suggest that the mechanism by which SCF supports PGC survival is by preventing PGC apoptosis. A similar action appears to be exerted by leukemia inhibitory factor (LIF), a further growth factor influencing PGC growth in culture. PGC proliferation seems to be mainly induced by cAMP dependent mechanisms, but further investigations are needed to clarify the interrelationships among the different molecular pathways activated by SCF, LIF, cAMP and other putative PGC growth factors (i.e. bFGF). Stimulation of long-term proliferation of PGCs, leading to derivation of ES-like cells (embryonal germ cells) obtained by using a combination of growth factors (bFGF, SCF and LIF), opens new intriguing perspectives for such studies and transgenic technology.

Stem cell factor and leukemia inhibitory factor promote primordial germ cell survival by suppressing programmed cell death (apoptosis)

Proliferating primordial germ cells (PGCs) isolated from mouse embryos soon after their arrival in the genital ridges would only survive in vitro at temperature of less than 30 degrees C (De Felici, M. and McLaren, A. (1983). Exp. Cell. Res. 144, 417–427; Wabik-Sliz, B. and McLaren, A. (1984). Exp. Cell. Res. 154, 530–536) or when co-cultured on cell feeder layers (Donovan, P. J., Stott, D., Godin, I., Heasman, J. and Wylie, C. C. (1986). Cell 44, 831–838; De Felici, M. and Dolci, S. (1991). Dev. Biol. 147, 281–284). In the present paper we report that mouse PGC death in vitro occurs with all the hallmarks of programmed cell death or apoptosis. We found that after 4–5 hours in culture many PGCs isolated from 12.5 dpc fetal gonads assumed a nuclear morphology and produced membrane bound fragments (apoptotic bodies) typical of apoptotic cells. In addition, PGCs in culture accumulated high level of tissue transglutaminase (tTGase; an enzyme that is induced and activated during apoptosis) and showed extensive degradation of DNA to oligonucleosomal fragments, which is characteristic of apoptosis. The physiological relevance of this mechanism of PGC death is supported by the finding that some PGCs undergoing apoptosis, as revealed by the high level of tTGase expression, were detected in the embryo. Most importantly, we show that the addition of stem cell factor (SCF) or leukemia inhibitory factor (LIF) to the culture medium, two cytokines known to favour PGC survival and/or proliferation in vitro, markedly reduced the occurrence of apoptosis in PGCs during the first hours in culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Combined action of stem cell factor, leukemia inhibitory factor, and cAMP on in vitro proliferation of mouse primordial germ cells

In the present paper we investigated the effects of stem cell factor/mastocyte growth factor (SCF/MGF), leukemia inhibitory factor/differentiating inhibitory activity (LIF/DIA) (two growth factors known to affect primordial germ cell growth in vitro) and forskolin (FRSK) (an activator of adenylate cyclase in many cell types) alone or in combination on the survival and proliferation of primordial germ cells (PGCs) obtained from 8.5, 10.5, and 11.5 days post coitum (dpc) mouse embryos and cultured without pre-formed cell feeder layers. The results showed that both at 1 and 3 days of culture the addition of 100 ng/ml SCF, 20 microM FRSK, or in some instances 20 ng/ml LIF alone caused a significant increase of PGC number as compared with controls. The highest effects were obtained when SCF and/or LIF were used together with FRSK. Moreover, we found that FRSK elevated cAMP levels in purified 11.5 dpc PGCs and that this compound, but not SCF and LIF, stimulated PGC proliferation, as assessed by 5-bromo-2'-deoxyuridin (BrdU) incorporation. These results suggest a mechanism of combined action of cAMP with SCF and/or LIF in the control of proliferation of mouse PGCs in vitro.

Proliferation of mouse primordial germ cells in vitro: a key role for cAMP

Two agents known to enhance the level of intracellular cAMP (dibutyryl cAMP and forskolin) markedly increase the number of 8.5, 10.5, and 11.5 days postcoitum (dpc) mouse primordial germ cells (PGCs) cultured on TM4 cell feeder layers. Forskolin (FRSK) caused a significant increase of PGC number also in monodispersed cell suspensions obtained from PGC-containing tissues of the three embryonic ages studied and in purified 11.5 dpc PGCs cultured without feeder layers. The addition to the culture medium of adenosine-3',5'-cyclic monophosphorothioate RP isomer (Rp-cAMPS, a competitive antagonist for cAMP-dependent protein kinases), significantly reduced the effects of FRSK. Last, FRSK stimulated PGC proliferation, as assessed by 5-bromo-2'-deoxyuridine incorporation. We conclude that cAMP-dependent mechanisms play a crucial role in the control of mitotic proliferation of mouse PGCs in culture.

Motor neuron diseases and amyotrophic lateral sclerosis: GM1 antibodies and paraproteinemia

Six of 110 patients (5.5%) with forms of motor neuron disease had abnormal titers of GM1 antibodies of 1:1,600 or higher. Four others came with previously known high titers. Three patients with upper motor neuron (UMN) signs had titers of 1,600; those with probable or no UMN signs had higher titers. Nine patients had conduction block; six of them had abnormal antibody titers, four with 6,400 or higher. Therefore, patients with motor neuron disease and abnormal anti-GM1 titers may have UMN signs or conduction block.

[Micropolyarteritis. The modern nosographic picture and a discussion of a clinical case]

Having observed a patient presenting micropolyarteritis with necrotic skin lesions, hypertension and renal injury, the authors had the opportunity to define more closely a disease that only recently has been recognized as a separate nosological entity within the vast and as yet not fully understood field of arterial disorders. In addition, recent literature on the subject is critically reviewed.

Cellular and molecular aspects of mouse primordial germ cell migration and proliferation in culture

The development of mouse primordial germ cells is followed from their first appearance in the extraembryonic mesoderm of the posterior amniotic fold (7 dpc embryo) to their settlement in the genital ridges (12.5 dpc embryo). The role of fibronectin as adhesive substrate and/or in stimulating cell motility during PGC migration is discussed. Recent papers showing how PGCs migrate when cultured in vitro on cellular monolayers are reviewed. The process of PGC homing is proposed to be controlled by chemotaxis as well by developmentally regulated cell-to-cell interactions. Finally, evidence that survival and proliferation of PGCs is strictly dependent on growth factors such as LIF and MGF, and possibly on a cAMP-dependent mechanism is reported.

[Hereditary angioedema. Description of a pediatric case]

Hereditary angioedema is a disease due to deficiency or functional anomaly of the serum inhibitor of C1-esterase, clinically characterised by the recurrence of oedematous episodes in the subcutis and mucosas; if not diagnoses in time, this condition is potentially fatal (up to 50% of cases for edema of the glottis). A case diagnosed in paediatric age is reported.

Motor neuron disease and amyotrophic lateral sclerosis: relation of high CSF protein content to paraproteinemia and clinical syndromes

From 1984 to 1988, 11 of 120 patients (9%) with motor neuron disease (MND) had paraproteins detected by serum immunofixation electrophoresis (IFE), compared with 4 (3%) by cellulose acetate gels: 1 patient had progressive spinal muscular atrophy, 5 patients had amyotrophic lateral sclerosis (ALS), and 5 patients had ALS with probable upper motor neuron signs. Four of 5 patients (80%) with cerebrospinal fluid (CSF) protein content above 75 mg/dl had paraproteins, as did 6 of 30 with values above 50 mg/dl. Four of 14 patients with cerebrospinal oligoclonal bands (OCB) also had paraproteins. Two patients with ALS, CSF protein content above 75 mg/dl, and paraproteinemia had lymphoma. We conclude the following about patients with MND: high CSF protein content (especially above 75 mg/dl) or CSF OCB makes paraproteinemia more likely; some of these patients may have lymphoma; there is an inordinately high occurrence of paraproteinemia in MND; and IFE on agarose is more sensitive than electrophoresis on cellulose acetate in detecting paraproteins. Syndromes of paraproteinemia and high CSF protein are not restricted to the lower motor neuron but qualify as "ALS" with coexisting upper motor neuron signs.

Long-term monitoring of D-lactic acidosis in a child

A case of D-lactic acidosis in a 2 1/2-year-old child followed for 11 months is reported. The infant had previously undergone extensive small intestinal resection for midgut volvulus. Diagnosis was confirmed by measurement of plasma D-lactate. Metabolic acidosis, increased anion gap, ataxia, and lethargy in patients with small intestinal resection warrant investigation for D-lactic acidosis. The presumed etiology is absorption of D-lactic acid produced by bacterial fermentation of carbohydrate in the colon. Antibiotic treatment resulted in prompt resolution of symptoms in this case. Prospective and prolonged monitoring of acidosis in patients with small bowel resection is encouraged.

Micromeasurement of plasma salicylate in arthritic children

A micromethod has been developed for determination of plasma salicylate. Frequent determinations of plasma salicylate levels in children with juvenile rheumatoid arthritis may be expected to provide greater therapeutic efficacy with reduced incidence of aspirin toxicity and consequently less need for use of secondary, more toxic, agents.