M?ssbauer spectroscopy, electron microscopy and electron diffraction studies of the iron cores in various human and animal haemosiderins

M?ssbauer spectroscopy has indicated significant differences in the iron-containing cores of various haemosiderins. In the present study, haemosiderin was isolated from a number of animal species including man. In addition, haemosiderin was isolated from patients with primary idiopathic haemochromatosis or with secondary (transfusional) iron-overload. The iron cores of the animal and normal human haemosiderin appear to be very similar by M?ssbauer spectroscopy, and the electron diffraction data indicate a ferrihydrite structure similar to that of ferritin cores. The haemosiderin isolated from secondary iron-overload shows anomalous behaviour in its temperature-dependent M?ssbauer spectra. This can be understood in terms of the microcrystalline goethite structure of the cores as indicated by electron diffraction. The haemosiderin cores obtained in the case of primary haemochromatosis have an amorphous Fe(III) oxide structure and show M?ssbauer spectra characteristic of a magnetically disordered material, which only orders at very low temperatures.     

Genetic and biochemical characterization of the galactose gene cluster in Kluyveromyces lactis.

We isolated and identified mutant strains of Kluyveromyces lactis that are defective for the Leloir pathway enzymes galactokinase, transferase, and epimerase, and we termed these loci GAL1 , GAL7 , and GAL10 , respectively. Genetic data indicate that these three genes are tightly linked, having an apparent order of GAL7 - GAL10 - GAL1 . This same gene order has been observed in Saccharomyces cerevisiae. Strains harboring gal7 mutations have elevated levels of beta-galactosidase, coded by an unlinked gene, galactokinase, and epimerase activities under uninduced conditions. We investigated the genetic basis of this constitutive gene expression and found no recombinants between the constitutive and Gal- phenotypes among 76 tetrads, suggesting that either GAL7 or a tightly linked gene codes for a regulatory function. This is the second gene that has been shown to specifically coregulate expression of the genes coding for beta-galactosidase and the Leloir pathway enzymes.     

Identification of Nitroso Compounds from Biotransformation of 2,4-Dinitrotoluene

The intermediates of microbial transformation of 2,4-dinitrotoluene by a mixed bacterial culture derived from activated sludge were identified as 2-amino-4-nitrotoluene, 4-amino-2-nitrotoluene, 2-nitroso-4-nitrotoluene, and 4-nitroso-2-nitrotoluene. The biotransformation of 2,4-dinitrotoluene occurred only under anaerobic conditions with an exogenous carbon source. The two nitroso compounds were unstable and could be observed only at the early stage of 2,4-dinitrotoluene anaerobic biotransformation.     

Drones are an effective tool to assess the impact of feral horses in an alpine riparian environment

Protected areas can be impacted by the presence and proliferation of feral species. Effective management of feral species requires reliable tools to monitor their population size and ecological impacts. Here, we used drone-based image analysis to assess evidence of feral horses and horse-specific ecological impacts on alpine riparian habitat. Valleys with low (0), medium (1–16) and high (>16) horse abundances were chosen for drone imagery analysis based on independent aerial counts of horses. Data collection trips were carried out pre- and post-2019/2020 wildfires, which unexpectedly burnt valleys with low horse presence. Drone-based RGB orthomosaic imagery was sufficient to identify seven indicators of horse presence and determine the severity of feral horse impacts. Despite the impact of fire, drone-derived classifications were able to accurately detect a gradient of horse impacts, showing a significant difference in indicators from low presence valleys compared with medium and high presence valleys, which did not differ significantly from each other. The significance of differences between valleys reveals that regions routinely inhabited by feral horses will display significant environmental impacts. Our results clearly indicated significant differences between valleys with low horse presence compared with either medium or high horse presence regions (0.01 for differences between both low and medium and low and high horse presence). This was evident both before and after the 2019/2020 fires, suggesting that wildfires did not significantly impact horse populations or distribution in the sampled region. Overall, it was evident that feral horses have a clear and definable impact on alpine riparian vegetation, and drone surveying can be used to routinely monitor potential spread and the outcome of management actions.     

The cellular localization of malonyl-coenzyme A decarboxylase in rat brain

Malonyl-coenzyme A (CoA) decarboxylase (E.C.4.1.1.9) activity in brain is low but steadily increases after birth. The main physiological role of this mitochondrial enzyme is thought to be the stabilization of malonyl-CoA levels which change very little with brain growth. In an effort to visualize malonyl-CoA decarboxylase by immunocytochemistry, and to determine its developmental changes, the enzyme was purified by an efficient small-scale procedure involving isolation of mitochondria, extraction at high ionic strength, isoelectric focusing, column chromatography, and preparative polyacrylamide gel electrophoresis. The enzyme from brain showed the same apparent molecular weight (160 kDa) and was immunoreactive with antisera raised against malonyl-CoA decarboxylase from liver. Immunocytochemistry revealed early and extensive labeling of hepatocytes in rat liver but only delayed visualization in the brain. Most nerve cells of the cerebral cortex and many microglia were stained but the neurons of the cerebellar cortex did not become reactive. Golgi epithelial cells and their processes, the Bergmann glia, also showed reaction product.     

Molecular evolution modeled as a fractal Poisson process in agreement with mammalian sequence comparisons

The fractal doubly stochastic Poisson process (FDSPP) model of molecular evolution, like other doubly stochastic Poisson models, agrees with the high estimates for the index of dispersion found from sequence comparisons. Unlike certain previous models, the FDSPP also predicts a positive geometric correlation between the index of dispersion and the mean number of substitutions. Such a relationship is statistically proven herein using comparisons between 49 mammalian genes. There is no characteristic rate associated with molecular evolution according to this model, but there is a scaling relationship in rates according to a fractal dimension of evolution. The FDSPP is a suitable replacement for the homogeneous Poisson process in tests of the lineage dependence of rates and in estimating confidence intervals for divergence times. As opposed to other fractal models, this model can be interpreted in terms of Darwinian selection and drift.      

Heat shock protein response to thermal stress in the Asiatic clam,Corbicula fluminea

A recent approach to evaluate environmenta induced damages has been damages has been suggested, based on the stress response. The approach involves the detection of stress protein induction in organisms to infer about environmental conditions in their surroundings. However, to be an indicator of adverse biological effects in the environment, the elevation of stress proteins should be compared to a response pattern for the experimental species. JuvenileCorbicula fluminea, collection from a control site, were submited to heat-shock stress in the laboratory to obtain the stress response pattern under normal and extreme conditions. Acclimated to 26°C, the specimens were submited to 29, 32, 35 and 38°C, for 96 h. After 1, 2, 4, 8, 24, 48, 72 and 96 h of exposure, clams were removed from each vial and prepared for stress protein analysis. Animals from the control site were frozen in liquid nitrogen at the time of collection, and prepared for stress protein analysis. Hsp60 and 70 were detected by immunoreactivity after separation on 12.5% polyacrylamide gels and transference to nitrocellulose by western blotting, to determine the stress protein concentrations. The result showed that hsp70 increased at 4h from the beginning of the experiment and progressed over the 96 h experimental period in animals exposed to 35°C. However hsp70 levels decreased between 4 h and 24 h for the clams stressed at their lethal temperature of 38°C. Immunoblotting with hsp60 showed similar reactivity. At 38°C there was an increase in the amount of hsp60 at 4h, reaching a maximum eight-fold level at 8h. By 96h, the amount decreased to levels lower than those observed at 4h. At 38°C the level of hsp60 began to decrease at 8 h and continue to decline to 24 h when the clams died. The data support the hypothesis of increasing concentrations of stress protein until the heat shock approaches the thermal limits for the species. The results of this research suggest the usefulness of using the stress response as a diagnostic in environmental toxicology. They confirm that the sps response may serve as a valid biomonitoring tool under chronic, sublethal exposures when it is still possible to prevent effects at organismal or higher organizational levels.     

The Int-2/Fgf-3 oncogene product is secreted and associates with extracellular matrix: implications for cell transformation.

NIH3T3 cells transformed by mouse Int-2/Fgf-3 cDNA express a series of Int-2-related products representing discrete stages of processing and glycosylation. We confirm that in at least two highly transformed clonal lines, Int-2 products acquire further modifications and are efficiently secreted into the culture medium. Secreted proteins become associated with the cell surface and extracellular matrix and can be displaced by addition of soluble glycosaminoglycans, specifically heparin, heparan sulfate, and dermatan sulfate. Increasing concentrations of heparin not only compete for Int-2 binding in a dose-dependent manner but also inhibit the growth of these cells and revert the transformed phenotype. These findings reaffirm the notion that extracellular or surface-bound Int-2 protein is instrumental in the morphological transformation of these cells.     

Receptor-induced phosphorylation by mammary-derived growth factor 1 in mammary epithelial cell lines.

Previous work has shown that a mammary-derived growth factor (MDGF1), a human milk-derived, acidic, 62-kDa, N-glycosylated growth factor binds to cell surface receptors and stimulates proliferation of mammary epithelial cells. An 18-amino acid N-terminal partial sequence of the factor did not show any homology to other known growth factors or proteins. Using polyclonal antiserum raised against the synthetic peptide, we demonstrated that conditioned medium prepared from human breast cancer cell lines contains the factor. The antibody could adsorb the biological activity of the factor present in the conditioned medium. Earlier experiments on receptor cross-linking indicated that the receptor was approximately 120-140 kDa. Since tyrosine phosphorylation plays a crucial role in cell proliferation and cell transformation, experiments were conducted to find out whether MDGF1 induces the appearance of phosphotyrosine in MDGF1-receptor-positive MDA-MB 468, MCF-7, and 184A1N4 cell lines compared to receptor-negative lines. Western blot analysis using monoclonal antiphosphotyrosine indicated that MDGF1 induces phosphotyrosine in a 180-185-kDa protein in MDGF1 receptor-positive cell lines. Phosphorylation was not blocked and phosphorylated proteins were not immunoprecipitated by an antibody directed against the binding site of the EGF receptor. Cell membrane fractionation demonstrated that phosphorylation induced by MDGF1 was membrane-associated. The nature of this 180-185-kDa protein and its possible relationship to the MDGF1 receptor are under investigation.