Assignment of the human homologue of Pim-1, a mouse gene implicated in leukemogenesis,to the pter-q12 region of chromosome 6

Summary Viral leukemogenesis in mice is frequently initiated by proviral activation of a highly conserved cellular gene called Pim-1. Here we report the chromosomal localization of the human homologue by Southern blot analyses of DNAs obtained from human-rodent somatic cell hybrids. The single copy human homologue was assigned to the 6pter-q12 segment.     

Interaction of C-phycocyanin with lipid monolayers under nitrogen and in the presence of air

The surface interaction of C-phycocyanin with lipids was studied using the monolayer technique. The surface activity of the protein was found to be higher at the lipid-water interface than at the nitrogen-water interface, particularly at high surface pressures of the lipid monolayer. The maximum initial surface pressures beyond which phycocyanin could not penetrate the dipalmitoylphosphatidylcholine and monogalactosyldiglycerol monolayers were 27 and 30 mN m-1, respectively. Below these values the protein demonstrated preferential interaction with the monogalactosyldiglycerol monolayer. The surface properties of the unfolded protein at pH 2.5 at the lipid-water interface were compared with those of the protein at pH 7.0. Higher affinity of the three-dimensional structure of the protein to lipid monolayers was observed, in particular by high subphase protein concentration. When the lipid films were subjected to oxidation stress by exposure to air, the surface properties of C-phycocyanin and dipalmitoylphosphatidylcholine were not greatly affected but the surface activity of monogalactosyldiacylglycerol was reduced dramatically by autoxidation. The oxidation of monogalactosyldiacylglycerol could not be prevented by the introduction of C-phycocyanin molecules at the lipid-water interface.     

M-MuLV-induced leukemogenesis: Integration and structure of recombinant proviruses in tumors

M-MuLV-specific DNA probes were used to establish the state of integration and amplification of recombinant proviral sequences in Moloney virus-induced tumors of Balb/Mo, Balb/c and 129 mice. The somatically acquired viral sequences contain both authentic M-MuLV genomes and recombinants of M-MuLV with endogenous viral sequences. All reintegrated genomes carry long terminal repeat (LTR) sequences at both termini of their genome. In the preleukemic stage a large population of cells exhibiting a random distribution of reintegrated M-MuLV genomes are seen, but during outgrowth of the tumor, selection of cells occurs leaving one or a few clonal descendants in the outgrown tumor. In this latter stage recombinant genomes can be detected. Although these recombinants constitute a heterogeneous group of proviruses, characteristic molecular markers are conserved among many individual proviral recombinants, lending credence to the notion that a certain recombinant structure is a prerequisite for the onset of neoplasia. The structure of these recombinants shows close structural similarities to the previously described mink cell focus-inducing (MCF)-type viruses.     

Similar C-phycocyanins from two strains of thermotolerant cyanophyte Mastigocladus laminousus.

C-phycocyanin from two strains of the thermotolerant blue-green alga, Mastigocladus laminosus (NZ-DB2-m and I-30-m), that grow within different temperature ranges have been characterized with respect to aggregation, immunologic properties, subunit composition, and thermodenaturation. The critical thermal-denaturation temperature for phycocyanin from both strains of M. laminosus phycocyanin is 60 degrees C which is higher than that for mesophilic phyococyanin. Immunodiffusion studied have shown that these two strains of M. laminosus exhibit no antigenic differences and are closely related to the mesophilic Plectonema calothricoides and the thermophilic Synechococcus lividus (strains 3). Neither phenol nor alpha-naphthol has any effect on phycocyanin aggregation in these two strains of M. laminosus. There is also no enhancement of formation of large aggregates at their elevated temperature of cultivation. Furthermore, the phycocyanin of both strains of M. laminosus does not demonstrate any large amount of 19S or higher aggregates at any pH value. These observations suggest that the mode of adaptation of M. laminosus phycocyanin to high temperature is differnet from the previously encountered. It is also important to note that phycocyanin is essentially unchanged whether it is extracted from the same strain, M. laminosus (NZ-DBS-m), grown at either 50 degrees C or 37 degrees C.     

Tissue-specific expression of a vimentin--desmin hybrid gene in transgenic mice.

We have introduced a hybrid gene, pVVim2, composed of the 5' region of the hamster vimentin gene encoding the head and rod domain of vimentin and the 3' region of the hamster desmin gene encoding the tail domain of desmin, into the germ line of mice by pronuclear injection. RNA and protein analysis of mice transgenic for this construct showed that the pVVim2 gene was expressed at high levels in a developmental and tissue-specific manner. This indicates that the vimentin-derived segment of the fusion gene contains all the regulatory elements required for vimentin-specific expression. Immunohistochemical staining of fibroblast cultures derived from the transgenic mice with antibodies specific for vimentin and desmin demonstrated that the pVVim2 protein is assembled into filaments that co-localize with the endogenous vimentin filaments. The expression of pVVim2 protein in mesenchymal cells does not interfere with the function of vimentin in these cells.     

Laser-transected microtubules exhibit individuality of regrowth, however most free new ends of the microtubules are stable

To study the possible mechanism of microtubule turnover in interphase cells, we have used the 266-nm wavelength of a short-pulsed Nd/YAG laser to transect microtubules in situ in PtK2 cells at predefined regions. The regrowth and shrinkage of the transected microtubules have been examined by staining the treated cells with antitubulin mAb at various time points after laser irradiation. The results demonstrate that microtubules grow back into the transected zones individually; neither simultaneous growth nor shrinkage of all microtubules has been observed. The half-time of replacement of laser-dissociated microtubules is observed to be approximately 10 min. On the other hand, exposure of the core of the microtubule, which is expected to consist almost completely of GDP-tubulin, by transecting the internal regions of the microtubule does not render the remaining polymer catastrophically disassembled, and most transected microtubules with free minus ends do not quickly disappear. Taken together, these results suggest that most microtubules in cultured interphase cells exhibit some properties of dynamic instability (individual regrowth or shrinkage); however, other factors in addition to the hydrolysis of GTP-tubulin need to be involved in modulating the dynamics and the stability of these cytoplasmic microtubules.     

Live attenuated pseudorabies virus expressing envelope glycoprotein E1 of hog cholera virus protects swine against both pseudorabies and hog cholera

To investigate whether live attenuated pseudorabies virus (PRV) can be used as a vaccine vector, PRV recombinants that expressed envelope glycoprotein E1 of hog cholera virus (HCV) were generated. Pigs inoculated with these recombinants developed high levels of neutralizing antibodies against PRV and HCV and were protected against both pseudorabies and hog cholera (classical swine fever).     

Prognostic factors in human primary breast cancer: comparison of c-myc and HER2/neu amplification.

Amplification of oncogenes in primary tumours may have prognostic and/or therapeutic significance for patients with breast cancer. We have studied HER2/neu and c-myc amplification together with steroid receptors in human primary breast tumours and related the outcome with (relapse-free) survival. A strong inverse correlation was found between HER2/neu amplification and the presence of oestrogen and progesterone receptors. Actuarial 5-years survival showed that breast cancer patients with c-myc amplification in their primary tumours experience a shorter relapse-free survival, especially in node-negative and in receptor-positive tumours, whereas HER2/neu amplification may be of prognostic value for overall survival in receptor-negative tumours. Overall, in our hands, c-myc amplification appeared to be a more potent prognosticator than HER2/neu amplification in human primary breast cancer.