Protease-mediated enhancement of lymphocyte-induced angiogenesis in X-ray irradiated mice

Angiogenesis was induced in mice by intradermal injection of semi-syngeneic splenocytes, and after three days the number of newly formed blood vessels at the injection site was counted. When recipients were total-body irradiated with 700 R 2 hours before the lymphocyte injection, the angiogenesis was significantly higher than in non-irradiated mice. The angiogenesis enhancement was of a systemic (not local) character as revealed in experiments with shielding of irradiated animals. This enhancement was not due to X-ray dependent immunosuppression, as shown in experiments with non-irradiated, pharmacologically immunosuppressed mice. Decreased angiogenesis was observed in irradiated mice after treatment with cortisone acetate, aprotinin, and EACA. The results suggest that proteases might be involved in mediating the angiogenesis enhancement after X-irradiation.     

Activation of Akt/protein kinase B overcomes a G(2)/m cell cycle checkpoint induced by DNA damage

Activation of Akt, or protein kinase B, is frequently observed in human cancers. Here we report that Akt activation via overexpression of a constitutively active form or via the loss of PTEN can overcome a G(2)/M cell cycle checkpoint that is induced by DNA damage. Activated Akt also alleviates the reduction in CDC2 activity and mitotic index upon exposure to DNA damage. In addition, we found that PTEN null embryonic stem (ES) cells transit faster from the G(2)/M to the G(1) phase of the cell cycle when compared to wild-type ES cells and that inhibition of phosphoinositol-3-kinase (PI3K) in HEK293 cells elicits G(2) arrest that is alleviated by activated Akt. Furthermore, the transition from the G(2)/M to the G(1) phase of the cell cycle in Akt1 null mouse embryo fibroblasts (MEFs) is attenuated when compared to that of wild-type MEFs. These results indicate that the PI3K/PTEN/Akt pathway plays a role in the regulation of G(2)/M transition. Thus, cells expressing activated Akt continue to divide, without being eliminated by apoptosis, in the presence of continuous exposure to mutagen and accumulate mutations, as measured by inactivation of an exogenously expressed herpes simplex virus thymidine kinase (HSV-tk) gene. This phenotype is independent of p53 status and cannot be reproduced by overexpression of Bcl-2 or Myc and Bcl-2 but seems to counteract a cell cycle checkpoint mediated by DNA mismatch repair (MMR). Accordingly, restoration of the G(2)/M cell cycle checkpoint and apoptosis in MMR-deficient cells, through reintroduction of the missing component of MMR, is alleviated by activated Akt. We suggest that this new activity of Akt in conjunction with its antiapoptotic activity may contribute to genetic instability and could explain its frequent activation in human cancers.     

Isolation and amino acid sequence of insulins and C-peptides of European bison (Bison bonasus) and fox (Alopex lagopus)

Insulins and C-peptides were extracted and purified from bison and fox pancreatic glands. The insulins were reduced and pyridylethylated, and the derived A- and B-chains separated by HPLC. Amino acid sequence determinations of the pyridylethylated A- and B-chains proved bisontine insulin to be identical to bovine insulin and fox insulin to be identical to dog and porcine insulin. Bisontine C-peptide proved to be identical to bovine C-peptide. The isolated fox C-peptide comprises 23 amino acid residues and probably represents a major tryptic fragment of a larger C-peptide. The fox C-peptide fragment is identical to the dog C-peptide (9-31) except for residue 3 (residue 11 in the dog C-peptide), which is aspartic acid as compared with glutamic acid in the dog C-peptide.     

The effect of mismatch repair and heteroduplex formation on sexual isolation in Bacillus.

In Bacillus transformation, sexual isolation is known to be an exponential function of the sequence divergence between donor and recipient. Here, we have investigated the mechanism under which sequence divergence results in sexual isolation. We tested the effect of mismatch repair by comparing a wild-type strain and an isogenic mismatch-repair mutant for the relationship between sexual isolation and sequence divergence. Mismatch repair was shown to contribute to sexual isolation but was responsible for only a small fraction of the sexual isolation observed. Another possible mechanism of sexual isolation is that more divergent recipient and donor DNA strands have greater difficulty forming a heteroduplex because a region of perfect identity between donor and recipient is required for initiation of the heteroduplex. A mathematical model showed that this heteroduplex-resistance mechanism yields an exponential relationship between sexual isolation and sequence divergence. Moreover, this model yields an estimate of the size of the region of perfect identity that is comparable to independent estimates for Escherichia coli. For these reasons, and because all other mechanisms of sexual isolation may be ruled out, we conclude that resistance to heteroduplex formation is predominantly responsible for the exponential relationship between sexual isolation and sequence divergence in Bacillus transformation.     

Mercury concentrations in hair exposed in vitro to mercury vapor

Hair is often used as an index of environmental and industrial exposure to different metals. The interpretation of metal levels in hair is difficult because of the risk of external contamination. The aim of this study was to define the degree of external contamination of hair exposed in vitro to mercury vapor. Specimens of hair were exposed to concentration: 0.026, 0.21, and 2.7 mg Hg/m³ for 2–28 d. Mercury levels in hair increased during 28 d of exposure 2, 3 and 13, times, respectively, when compared to initial values. Mercury levels in hair exposed to the first and second (but not third) concentration of mercury vapor attained a steady state on the 21st d of exposure. The contamination of hair with mercury could not be removed by washing with water, solvent, and detergent. Hair may be used as an index of internal uptake of mercury provided that it was not externally exposed to mercury vapor. In cases of occupational exposure to mercury vapor, hair could become a useful tool for monitoring exposures.     

Critical Evaluation of Phosphate Solubilizing Pseudomonads Isolated from a Partially Recultivated Potash Tailings Pile

Ten phosphate solubilizing pseudomonads isolated from a partially recultivated potash tailings pile in Germany were characterized and tested for their potential to assist in the ongoing recultivation process. Despite fertilization, the plants which are grown for recultivation show phosphate deficiency symptoms, and therefore the isolates are intended to be used as biofertilizer inoculants. On agar plates incubated at five different temperatures, some of the strains showed a temperature-dependent ability to solubilize tricalcium phosphate, while others performed the same at any given temperature. In liquid medium, the isolates solubilized between 271 and 730 μg ml(-1) of phosphate from tricalcium phosphate. Both the weakest (designated S10) and the strongest solubilizing strain (S06) were further tested for their viability during solubilization. In an assay over the course of 1 week, both strains released their maximum amount of phosphate after 2-4 days. At that later point of time, however, viable cells of isolate S06 were no longer detectable, whereas the weaker strain S10 could be cultured after 1 week in broth. Taking all in vitro observations into account, the usability of the isolates as biofertilizers is critically discussed regarding both the in situ conditions on the tailings pile and the lowered viability due to the excess production of organic acids.     

Dietary characteristics of co-occurring polar cod (<Emphasis Type="Italic">Boreogadus saida</Emphasis>) and capelin (<Emphasis Type="Italic">Mallotus villosus</Emphasis>) in the Canadian Arctic,Darnley Bay

Reduction in sea ice due to climate change is expected to have a negative impact on habitat availability for Arctic marine fishes and induce range expansion of species from southern environments. Such an effect will likely be observed in the abundance of polar cod, Boreogadus saida (Lepechin, 1774), as well as interspecific interactions of this intermediate-level trophic taxon, particularly in more southerly fringing seas in the Arctic. Polar cod and capelin, Mallotus villosus (Müller, 1776), are pelagic, planktivorous forage fishes, which occupy similar dietary niches and are the primary prey of marine predators. Co-occurring polar cod and capelin were collected at seven stations in Darnley Bay, NT, during August 2013. Standard length (SL), used as a proxy for age, suggested that polar cod (mean ± 1 SD: 71.1 ± 10.3 mm) were predominantly age 1+ and capelin (96.2 ± 13.4 mm) were mostly age 2+. Stomach content analyses indicated that both species feed extensively on calanoid copepods (Calanus hyperboreus, C. glacialis, Metridia longa) and amphipods (Themisto libellula). There was high dietary overlap between capelin and polar cod, evidenced by Schoener’s index (0.80). Additionally the quantity of dietary items, biomass and energetic content consumed differed among size classes in both capelin (SL, 70.5–132.0 mm) and polar cod (SL, 42.1–114.4 mm). This study illustrates that the diets of these sympatric forage fishes in an Arctic ecosystem are very similar, indicating a high potential for interspecific competition as the sub-Arctic capelin expands its range into Arctic regions with climate change.