Glutamate Oxidation by Soybean Cotyledon and Leaf Mitochondria

Mitochondria purified from cotyledons of soybean seedlings fiveto ten days old have the capacity to rapidly oxidize glutamate(measured as glutamate dependent oxygen consumption). This capacitywas greatest at ten days after planting but was very low priorto emergence of cotyledons from the vermiculite and during senescence.Solubilized glutamate dehydrogenase activity, on the other hand,was substantial at two days after planting, peaked at sevendays, then declined and rose again during senescence. It issuggested that mitochondrial glutamate oxidation plays a rolein reserve mobilization and amino acid metabolism during seedlinggrowth. Leaf mitochondria and those from senescing cotyledonscould not sustain rapid rates of glutamate oxidation despiteready oxidation of other substrates and high solubilized glutamatedehydrogenase activity, suggesting an alternative role for theenzyme in these tissues. Possible controlling factors are discussed. ² Present address, Garvan Institute, Darlinghurst, N. S. W.,Australia. ³ Permanent address, Department de Biologia Vegetal, Facultatde Biologia, Universitat de Barcelona, Barcelona, Spain. (Received May 6, 1988; Accepted August 3, 1988)     

Inverted neurons in agyria

Summary An anatomoclinical observation of agyria is reported. The karyotype revealed a partial deletion of the short arm of chromosome 17. The etiology of agyria is reviewed in the light of this chromosomal abnormality. In addition we describe the peculiar pattern of neurons in the cortex: Golgi stain demonstrated many inverted pyramidal cells in the superficial part of the cortical layer. The mechanism of this abnormality is discussed.     

Developmentally regulated thyroid hormone distributor proteins in marsupials, a reptile, and fish

Thyroid hormones are essential for vertebrate development. There is a characteristic rise in thyroid hormone levels in blood during critical periods of thyroid hormone-regulated development. Thyroid hormones are lipophilic compounds, which readily partition from an aqueous environment into a lipid environment. Thyroid hormone distributor proteins are required to ensure adequate distribution of thyroid hormones, throughout the aqueous environment of the blood, and to counteract the avid partitioning of thyroid hormones into the lipid environment of cell membranes. In human blood, these proteins are albumin, transthyretin and thyroxine-binding globulin. We analyzed the developmental profile of thyroid hormone distributor proteins in serum from a representative of each order of marsupials (M. eugenii; S.crassicaudata), a reptile (C. porosus), in two species of salmonoid fishes (S. salar; O. tshawytsch), and throughout a calendar year for sea bream (S. aurata). We demonstrated that during development, these animals have a thyroid hormone distributor protein present in their blood which is not present in the adult blood. At least in mammals, this additional protein has higher affinity for thyroid hormones than the thyroid hormone distributor proteins in the blood of the adult. In fish, reptile and polyprotodont marsupial, this protein was transthyretin. In a diprotodont marsupial, it was thyroxine-binding globulin. We propose an hypothesis that an augmented thyroid hormone distributor protein network contributes to the rise in total thyroid hormone levels in the blood during development.     

Pollution and Its Impact on Wild Animals: A Meta-Analysis on Oxidative Stress

Oxidative stress is the unifying feature underlying the toxicity of anthropogenic pollution (e.g., heavy metals, polycyclic aromatic hydrocarbons, and nitrogen-oxides) and the ultimate culprit in the development of many diseases. Yet, there has been no attempt to summarize the published data on wild terrestrial animals to reveal general trends regarding the effects of pollution on oxidative stress. The main findings of this meta-analysis reveal that, as predicted, there is an overall increase in oxidative stress when exposed to pollution. This is mainly due to a weak overall increase of oxidative damages, although there is some variation across taxa. The reduced form of glutathione (GSH) and its associated enzymes are the most reliable biomarkers. This result is important when choosing biomarkers and when using less-invasive sampling of endangered species, or for longitudinal approaches. To be able to predict future population outcomes, possible treatments, but also evolutionary responses to a changing environment, a greater integration of biotic factors such as temperature, bioavailability of toxic elements, and species-specific responses are needed.     

Mecardonia tenella (Plantaginaceae) Attracts Oil-, Perfume-, and Pollen-Gathering Bees in Southern Brazil

Floral characteristics often indicate the pollinators' functional group visiting the plant and the pollination syndromes associated with them. This idea has been challenged in the past decades due to increasing evidence that most plants, including those exhibiting floral syndromes, are visited by large arrays of species that differ in their effectiveness as pollinators. Our study focuses on Mecardonia tenella (Plantaginaceae) from the Araucaria forest of southern Brazil, which exhibits characteristics of the oil flower pollination syndrome. However, it is visited by three types of functional groups of bees: male orchid bees, oil-collecting bees, and pollen-seeking bees. The relative contribution of each functional group to the plant's reproductive success was estimated based on their pollen load, visitation frequency, and morphology. We assessed resources, phenology, and breeding system of M. tenella . Our results indicate that flowers lack nectar, but volatiles, lipids, and pollen are resources that can be gathered by visitors. This combination of floral traits and visitors' assemblage makes M. tenella a challenge to the concept of pollination syndromes. Our findings indicate that the current interactions may not reflect the circumstances under which some floral traits of this plant were selected.     

Matrix metalloproteinase 13 is induced in fibroblasts in polyomavirus middle T antigen-driven mammary carcinoma without influencing tumor progression

Matrix metalloproteinase (MMP) 13 (collagenase 3) is an extracellular matrix remodeling enzyme that is induced in myofibroblasts during the earliest invasive stages of human breast carcinoma, suggesting that it is involved in tumor progression. During progression of mammary carcinomas in the polyoma virus middle T oncogene mouse model (MMTV-PyMT), Mmp13 mRNA was strongly upregulated concurrently with the transition to invasive and metastatic carcinomas. As in human tumors, Mmp13 mRNA was found in myofibroblasts of invasive grade II and III carcinomas, but not in benign grade I and II mammary intraepithelial neoplasias. To determine if MMP13 plays a role in tumor progression, we crossed MMTV-PyMT mice with Mmp13 deficient mice. The absence of MMP13 did not influence tumor growth, vascularization, progression to more advanced tumor stages, or metastasis to the lungs, and the absence of MMP13 was not compensated for by expression of other MMPs or tissue inhibitor of metalloproteinases. However, an increased fraction of thin collagen fibrils was identified in MMTV-PyMT;Mmp13(-/-) compared to MMTV-PyMT;Mmp13(+/+) tumors, showing that collagen metabolism was altered in the absence of MMP13. We conclude that the expression pattern of Mmp13 mRNA in myofibroblasts of invasive carcinomas in the MMTV-PyMT breast cancer model recapitulates the expression pattern observed in human breast cancer. Our results suggest that MMP13 is a marker of carcinoma-associated myofibroblasts of invasive carcinoma, even though it does not make a major contribution to tumor progression in the MMTV-PyMT breast cancer model.     

Evidence for the mechanism of the irreversible inhibition of oestrone sulphatase (ES) by aminosulphonate based compounds

In our search for the mechanism of the enzyme oestrone sulphatase (ES) we have synthesised and evaluated a number of compounds that were predicted to possess some inhibitory activity. Some of these compounds were indeed found to be inhibitors of ES, whilst other compounds were not. From a consideration of the structure–activity relationship (SAR) of the inhibitors and non-inhibitors of this enzyme, we discovered a factor which we now believe is the main inhibitory moiety within the aminosulphonated inhibitors. We therefore report the results of our study into a series of phenyl and alkyl sulphamated compounds as inhibitors of ES. The results of the study show that the substituted phenyl sulphamates are potent inhibitors, whereas the alkyl compounds are, in general, non-inhibitors. Using the results of our SAR study, we postulate the probable mechanism for the irreversible and reversible inhibition of ES, and rationalise the role of the different physicochemical factors in the inhibition of this crucial enzyme.