115DIMETHYLSULPHOXIDE AND 1,2-PROPANEDIOL DIFFERENTIALLY CRYOPROTECT BOVINE AND PORCINE PRIMORDIAL, PRIMARY AND SECONDARY FOLLICLES

Ovarian tissue cryopreservation is of interest for many areas of assisted reproduction. Normal structure and intra- as well as intercellular organization have to be maintained in order to preserve follicle viability. In the present work we studied the effects of two largely used cryoprotectants, namely, dimethylsulphoxide (DMSO) and 1,2-propanediol (PROH), on follicle morphology. Experiments were carried out on bovine and porcine ovaries and the two cryoprotectants were assessed for their ability to preserve structural integrity of primordial, primary and secondary follicles, in order to investigate the protective effects of these molecules on specific developmental stages. Fragments from each ovary were divided in three groups: a) immediately fixed (control); b) cryopreserved in 1.5M DMSO; c) cryopreserved in 1.5M PROH. To allow equilibration with the cryoprotectant, samples were held for 30min at 4°C in order to minimize toxic effects. Cryopreservation was carried out in a controlled rate freezer (Planer Planerple, Sunbury, Middlesex, UK), with the following protocol: precooling (4°C); cooling at −2°C/min to 9°C; seeding at 9°C and standby for 10 minutes; cooling at −0.3°C/min to 40°C and 10°C/min to 140°C; plunging into liquid nitrogen. Samples were rapidly thawed. Dilution of cryoprotectants was carried out in 3 steps of ten minutes each at 4°C (1M; 0.5M; 0M). Samples were then fixed, paraffin embedded, serially sectioned and evaluated with a Nikon TE200 inverted microscope. Follicles of each developemental stage were scored in three categories using the criteria previously described by Paynter et al. (1999, Cryobiology 38, 301–309) and presented in the table below as I=Intact; SA=Small Abnormalities; GA=Great Abnormalities. Statistical differences were assessed by the chi-square test (P<0.05). The results obtained showed that both cryoprotectants are effective for the preservation of secondary follicles. The use of PROH was unable to protect primary and primordial follicles in both species. Conversely, DMSO showed a satisfying cryoprotecting effect for pig primary and bovine primordial follicles but had a poor protecting capability for pig primordial and bovine primary follicles. Altogether the present results suggest that the choice of the cryoprotectant needs to be carefully targeted in relation to the follicular stage and the species of interest. This work was funded by Industria Farmaceutica Serono SpA. Table 1

Involvement of PI3K in PKCepsilon-mediated oncogenic signal in rat colonic epithelial cells

We have recently demonstrated that overexpression of PKCepsilon is oncogenic in colonic epithelial cells. To test whether PI3K might be an upstream effector of PKCepsilon in cell transformation, we have overexpressed the p110alpha PI3K subunit in non-transformed D/WT colonic epithelial cells. Transfectants displayed the major in vitro features of transformed cells. Interestingly, no transformation occurred when p110alpha was co-transfected with a dead-kinase PKCepsilon mutant. The p85alpha subunit of PI3K, displaying a dominant-negative-like effect, was then transfected in PKCepsilon-transformed D/epsilon cells. The transformed profile of these cells was markedly reduced. To identify which by-products of PI3K might be involved in cell transformation we have transfected the D/WT cell line with cDNAs encoding the PI3 kinases hVps34 and C2beta. Overexpression of hVps34 did not cause cell transformation. Conversely, in vitro transformation was observed when C2beta was transfected into D/WT cells. These results indicate that phosphatidylinositol-3 monophosphate does not seem to be involved in cell transformation, and that phosphatidylinositol-3,4 bisphosphate and phosphatidylinositol-3,4,5 trisphosphate are more likely involved in this process. Thus, our data support the hypothesis of a linkage between PI3K and PKCepsilon, and indicate that PI3K may act as a source of second messengers responsible for oncogenic activation of PKCepsilon.

Functional significance of intermediate filament meshwork in annelid helical muscles

A desmin-like protein of mol wt 54 kDa was identified in the body wall muscles of some Polychaeta, Oligochaeta, and Hirudinea utilizing SDS-PAGE followed by blot and screening with a vertebrate anti-desmin antibody. The pattern in immunofluorescence is compared to electron micrographs where several bundles of filamentous structures are clearly identifiable. These bundles are unevenly arranged in round or flattened circomyarian fibers and sometimes clearly connect Z elements with hemidesmosomes. The mechanism of intermediate filaments as a functional integration in muscle fibers is analyzed and a possible role as a block to superelongation typical of helical muscles is discussed.

Flight muscle differentiation in nymphs of a dragonfly Anax imperator

Flight muscle fibers of Anax imperator nymphs, in different developmental stages are analyzed for several morphological features, such as the arragnement and numerical ratio of actin and myosin filaments, the pattern of the T system and sarcoplasmic reticulum, the number of microtubules and the fractional volume of mitochondria in each fiber. The T system is initially represented by longitudinal grooves on the cell surface, joined with vesicles of the sarcoplasmic reticulum; this pattern rapidly changes and the grooves start to break up into longitudinal segments. The thin to thick filament ratio is at first quite high (about 4-4.5:1) but rapidly falls to the final (3:1) when the myofibrils are well developed at the fiber periphery. Statistical analyses show that the measured values are significantly different in the various stages of development, also indicating a progressive reduction of the ratio variability. The reduction of thin to thick filament ratio and the variance decrease fit quite well with the hypothesis that the synthesis of actin and myosin depends on independently regulated messenger RNA molecules.