Changes in the expression profiles of claudins during gonocyte differentiation and in seminomas.

Testicular germ cell tumors (TGCTs) are the most common type of cancer in young men and their incidence has been steadily increasing for the past decades. TGCTs and their precursor carcinoma in situ (CIS) are thought to arise from the deficient differentiation of gonocytes, precursors of spermatogonial stem cells. However, the mechanisms relating failed gonocyte differentiation to CIS formation remain unknown. The goal of this study was to uncover genes regulated during gonocyte development that would show abnormal patterns of expression in testicular tumors, as prospective links between failed gonocyte development and TGCT. To identify common gene and protein signatures between gonocytes and seminomas, we first performed gene expression analyses of transitional rat gonocytes, spermatogonia, human normal testicular, and TGCT specimens. Gene expression arrays, pathway analysis, and quantitative real-time PCR analysis identified cell adhesion molecules as a functional gene category including genes downregulated during gonocyte differentiation and highly expressed in seminomas. In particular, the mRNA and protein expressions of claudins 6 and 7 were found to decrease during gonocyte transition to spermatogonia, and to be abnormally elevated in seminomas. The dynamic changes in these genes suggest that they may play important physiological roles during gonocyte development. Moreover, our findings support the idea that TGCTs arise from a disruption of gonocyte differentiation, and position claudins as interesting genes to further study in relation to testicular cancer.

Developmental expression of the translocator protein 18 kDa (TSPO) in testicular germ cells.

Translocator protein (TSPO) is a high affinity 18 kDa drug- and cholesterol-binding protein strongly expressed in steroidogenic tissues where it mediates cholesterol transport into mitochondria and steroid formation. Testosterone formation by Leydig cells in the testis is critical for the regulation of spermatogenesis and male fertility. Male germ cell development comprises two main phases, the pre-spermatogenesis phase occurring from fetal life to infancy and leading to spermatogonial stem cell (SSC) formation, and spermatogenesis, which consists of repetitive cycles of germ cell mitosis, meiosis and differentiation, starting with SSC differentiation and ending with spermiogenesis and spermatozoa formation. Little is known about the molecular mechanisms controlling the progression from one germ cell phenotype to the next. Here, we report that testicular germ cells express TSPO from neonatal to adult phases, although at lower levels than Leydig cells. TSPO mRNA and protein were found at specific steps of germ cell development. In fetal and neonatal gonocytes, the precursors of SSCs, TSPO appears to be mainly nuclear. In the prepubertal testis, TSPO is present in pachytene spermatocytes and dividing spermatogonia. In adult testes, it is found in a stage-dependent manner in pachytene spermatocyte and round spermatid nuclei, and in mitotic spermatogonia. In search of TSPO function, the TSPO drug ligand PK 11195 was added to isolated gonocytes with or without the proliferative factors PDGF and 17ß-estradiol, and was found to have no effect on gonocyte proliferation. However, TSPO strong expression in dividing spermatogonia suggests that it might play a role in spermatogonial mitosis. Taken together, these results suggest that TSPO plays a role in specific phases of germ cell development.

Dehydroacetic acid as a reagent for the separation and gravimetric determination of copper(II), aluminium and beryllium.

Dehydroacetic acid is proposed as a reagent for the gravimetric determination of copper(II), aluminium and beryllium at pH 3.0-6.0, 3.0-6.0 and 7.5-9.5 respectively. Copper is weighed as the complex Cu(C(8)H(7)O(4))(2). Aluminium and beryllium are weighed as Al(2)O(8) and BeO. The reagent is easy to prepare.

Pyridine-2-aldoxime and 6-methylpyridine-2-aldoxime as gravimetric reagents for estimation of palladium(II) and uranium(VI).

Pyridine-2-aldoiumc (I) has been found to be a sensitive reagent for the gravimetric determination of palladium(II). From chloride medium, precipitation is complete at pH 3.0-11.0, and in solution containing 1NHNO(3) to pH6.0. The compositions of the precipitates (dried at 130 degrees ) correspond to PdL(2), and PdL(2). HNO(3) (HL representing the reagent) respectively. Pd(II) can be estimated gravimetncally in presence of acetate, oxalate, tartrate, phosphate, fluoride borate, perchlorate, Cu(II), Cd, Co(II), Fe(II), Ni, Zn, Pb, Bi, Sb(III), Pt(IV), Ir(IV), Ru(III), Rh(III); Os(IV) in quantities more than twice that of Pd(II), and Ag(I), Au(III) and Fe(II) even m traces cause serious interference. The yellow uranium(VI) complex with (I) is precipitated quantitatively over the pH range 3.5-10.5 and, after washing and drying corresponds to the composition (c(6)h(5)n(2)o)(2)uo(2), The uranium(VI) complex with 6-methylpyridine-2-aldoxime (II) is precipitated quantitatively over the pH range 3.0-10.5, and after washing and drying at 120-130 degrees corresponds to UO(2),(C(7),H(7),N(2)O)(2). Both (I) and (II) are suitable for the estimation of 1-50 mg of uranium(VI) in the presence of up to 10-fold quantities ofTh(IV), La(III) and Ce(III) even when present together. Ce(IV) in quantities more than three times that of U must be reduced to Ce(III). Tartrate, citrate, phosphate, Ti(IV) and Zr interfere, but acetate, oxalate, and borate do not.

Spectrophotometric determination of ruthenium(III) and iridium(TV) with 8-hydroxyquinoIine N-oxide.

The spectrophotometric characteristics and the stability constants of the yellow to brown 1:1 and 1:2 complexes of platinum metals with oxine N-oxide (existing as chloro mixed-ligand complexes) have been investigated. Oxine N-oxide can be used as a spectrophotometric reagent for ruthenium(III) and iridium(IV).

Spectrophotometric determination of osmium(IV), iridium(IV) and platinum(iv) and separation and determination of palladium(II) and ruthenium(III) in the presence of other platinum metals, with oximidobenzotetronic acid as reagent.

Oximidobenzotetronic acid is suggested as a reagent for the spectrophotometric determination of osmium(IV), iridium(III), iridium(IV), platinum(IV) and for separation and determination of palladium(II) and ruthenium(III) in the presence of other platinum metals. Iridium(III) and (IV) can be estimated when present together.

Rapid spectrophotometric determination of cobalt after extraction using oximidobenzotetronic acid.

A spectrophotometric method based on the extraction of cobalt with benzene solutions of oximidobenzotetronic acid (OBTA) is proposed for the estimation of 0.2-3.0 ppm of cobalt. The 3:1 OBTA : Co complex containing cobalt(III) has its absorption maximum at 430 nm; its molar absorptivity in benzene is 1.82 x 10(3)L. mole(-1). mm(-1). Since the blue iron(II) complex is not extracted into benzene, iron(II) and cobalt(II) can be separated and determined spectrophotometrically.

Spectrophotometric studies of ruthenium(III)and rhodium(III)-oximidobenzotetronic acid complexes and the simultaneous determination of the two metals.

Ruthenium(III) and rhodium(III) form stable coloured complexes in ethanolic solution with oximidobenzotetronic acid (OBTA). Ruthenium forms a purple-violet Ru(OBTA)(3) complex at pH 1.1-3.5, which is stable over the pH range 1.1-11.3. Rhodium(III) forms a yellowish-brown complex, RhCl(2)(OBTA)(2), at pH 2-8; at higher pH (11.5 and above) the complex is reddish-brown, but has the same Rh:OBTA ratio. A method for the simultaneous determination of these two metals is proposed, and the interference by commonly occurring ions has been investigated.