Enzymic conversion of agmatine to putrescine in Lathyrus sativus seedlings. Purification and properties of a multifunctional enzyme (Putrescine synthase)

The participation of a multifunctional enzyme (a single polypeptide with multiple catalytic activities (14)) has been demonstrated in the conversion of agmatine to putrescine in Lathyrus sativus seedlings. This enzyme (putrescine synthase) with inherent activities of agmatine iminohydrolase, putrescine transcarbamylase, ornithine transcarbamylase, and carbamate kinase has been purified to homogeneity and has Mr = 55,000. In the presence of inorganic phosphate, the enzyme catalyzed the stoichiometric conversion of agmatine and ornithine to putrescine and citrulline, respectively. The different activities associated with the enzyme copurified with near constancy in their specific activity. The enzyme catalyzed phosphorolysis and arsenolysis of N-carbamyl putrescine. The multifunctionality of putrescine synthase was also supported by 1) activity staining, 2) intact transfer of the ureido-14C group from labeled N-carbamyl putrescine to ornithine to form citrulline, and 3) the affinity of the enzyme toward structurally and functionally related affinity matrices. An agmatine cycle is proposed wherein N-carbamyl putrescine arising from the agmatine iminohydrolase reaction is converted to putrescine and citrulline, with the ureido group of N-carbamyl putrescine being transferred intact to ornithine. Preliminary results indicate that this series of reactions is also present in other plants

Isolation of sheep anterior pituitary messenger RNA and its translation in a heterologous cell-free system

A preparation rich in the specific messenger RNA involved in the synthesis of prolactin from sheep anterior pituitary glands was obtained by employing both the immunochemical and affinity techniques. A dose-dependent and efficient stimulation of protein synthesis by the isolated total pituitary RNA as well as poly (A) rich RNA were achieved with the reticulocyte system. The synthesis of prolactin as one of the translational products of this cell-free system was established by specific immunoprecipitation followed by resolution on sodium dodecyl sulphate polyacrylamide gel electrophoresis

Modulation of testicular lutropin receptors in the developing male rat

In the developing male rat around 40 days of age, the testis appears to contain the maximum amount of lutropin receptors per unit weight. During this period, circulating levels of testosterone markedly increase without the concomitant major surges in lutropin levels. The increased sensitivity and responsiveness of tests to basal levels of circulating lutropin during this period is accompanied by enhanced serum prolactin levels suggesting that this hormone may be involved in this process. The finding that prolactin treatment of pubertal rats for 3 days induced the formation of more testicular lutropin receptors supports the above premise. However, shortterm immunoneutralisation of endogenous prolactin did not significantly alter the specific binding of [125I]-labelled lutropin to testicular membranes. Interestingly, during development, a close correction exists between receptor occupancy and capacity of the tissue to bind labelled lutropin. The apparent dissociation between serum lutropin levels, on the one hand and tissue occupancy and free receptor contents on the other, suggests that factors other than lutropin (presumably prolactin) are involved in the modulation of the sensitivity and the responsiveness of the testis to lutropin during early development

Amino acid interrelationships in cysteine toxicity in Neurospora crassa

L-Cysteine became toxic to the growth of Neurospora crassa (wild, Em 5297a), in the range 1.0-2.0 mM in the culture medium. The specificity of cysteine toxicity was shown by absence of toxicity with other sulphydryl compounds (β -mercaptoethanol, thioglycollic acid, reduced glutathione) and with cysteine metabolites, L-cysteic acid and taurine, under similar conditions. The toxicity of L-cysteine was completely overcome by supplements of S-methyl-L-cysteine and to a marked extent by DL-methionine and DL-homocysteine; partial counteraction of cysteine toxicity was observed with L-serine, DL-tryptophan, DL-alanine, DL-valine, DL-homoserine or DL-threonine. DL-Methionine and S-methyl-L-cysteine counteracted the inhibitory effect of L-cysteine in two N. crassa mutants, namely, methionineless mutant 38706 and cystathionineless mutant 9666

Riboflavin carrier protein: a serum and tissue marker for breast carcinoma

We have earlier shown that the estrogen-modulated riboflavin carrier protein (RCP) first isolated from the chicken egg is evolutionarily conserved in mammals and is elaborated by lactating mammary gland as demonstrated with rat mammary epithelial cells in culture and confirmed by isolation of the vitamin carrier from bovine milk. In view of several earlier reports that many milk proteins as well as other estrogen-inducible proteins are up-regulated and secreted into circulation in animal models and in women with neoplastic breast disease, we analyzed serum RCP levels in a double-blind study using a specific radioimmunoassay in pre- and post-menopausal women with clinically diagnosed breast cancer at early and advanced stages of the disease and compared these levels with those in normal age-matched control volunteers. Our data reveal that the serum RCP levels in cycling breast cancer patients are 3- to 4-fold higher (p < 0.01) than those in their normal counterparts. This difference in circulatory RCP levels between cancer patients and their age-matched normal counterparts is further magnified to 9- to 11-fold (p < 0.005) at the post-menopausal stage. In addition, there seems to be a good correlation between rising RCP levels and disease progression, since significantly higher RCP concentrations (p < 0.005) are encountered in patients with advanced metastasizing breast cancer versus those with early disease. Using specific monoclonal antibodies, RCP could be localized immunohistochemically in the cytoplasm of invading neoplastic cells of lobular and ductal carcinomas of the breast, indicating that the malignant cells are probably the source of the elevated serum RCP levels in breast cancer. These findings suggest that measurement of circulatory RCP and the immunohistochemical staining pattern of RCP in biopsy specimens could be exploited as an additional marker in diagnosis/prognosis of breast cancer in women

Mitochondrial dysfunction and oxidative stress caused by cryopreservation in reproductive cells

Mitochondria, fundamental organelles in cell metabolism, and ATP synthesis are respon-sible for generating reactive oxygen species (ROS), calcium homeostasis, and cell death. Mitochon-dria produce most ROS, and when levels exceed the antioxidant defenses, oxidative stress (OS) is generated. These changes may eventually impair the electron transport chain, resulting in decreased ATP synthesis, increased ROS production, altered mitochondrial membrane permeability, and dis-ruption of calcium homeostasis. Mitochondria play a key role in the gamete competence to facilitate normal embryo development. However, iatrogenic factors in assisted reproductive technologies (ART) may affect their functional competence, leading to an abnormal reproductive outcome. Cry-opreservation, a fundamental technology in ART, may compromise mitochondrial function leading to elevated intracellular OS that decreases sperm and oocytes’ competence and the dynamics of fertilization and embryo development. This article aims to review the role played by mitochondria and ROS in sperm and oocyte function and the close, biunivocal relationships between mitochon-drial damage and ROS generation during cryopreservation of gametes and gonadal tissues in different species. Based on current literature, we propose tentative hypothesis of mechanisms involved in cryopreservation-associated mitochondrial dysfunction in gametes, and discuss the role played by antioxidants and other agents to retain the competence of cryopreserved reproductive cells and tissues

A Rare Cause of Renal Mass; A Case Study

A seventy five year old gentleman with the clinical diagnosis of renal tuberculosis was found to have renal squamous cell carcinoma. The clinical presentation and management are being discussed

Boxicity of graphs on surfaces

The boxicity of a graph $G=(V,E)$ is the least integer $k$ for which there exist $k$ interval graphs $G_i=(V,E_i)$, $1 \le i \le k$, such that $E=E_1 \cap ... \cap E_k$. Scheinerman proved in 1984 that outerplanar graphs have boxicity at most two and Thomassen proved in 1986 that planar graphs have boxicity at most three. In this note we prove that the boxicity of toroidal graphs is at most 7, and that the boxicity of graphs embeddable in a surface $\Sigma$ of genus $g$ is at most $5g+3$. This result yields improved bounds on the dimension of the adjacency poset of graphs on surfaces.Comment: 9 pages, 2 figure

Expanding the expressive power of Monadic Second-Order logic on restricted graph classes

We combine integer linear programming and recent advances in Monadic Second-Order model checking to obtain two new algorithmic meta-theorems for graphs of bounded vertex-cover. The first shows that cardMSO1, an extension of the well-known Monadic Second-Order logic by the addition of cardinality constraints, can be solved in FPT time parameterized by vertex cover. The second meta-theorem shows that the MSO partitioning problems introduced by Rao can also be solved in FPT time with the same parameter. The significance of our contribution stems from the fact that these formalisms can describe problems which are W[1]-hard and even NP-hard on graphs of bounded tree-width. Additionally, our algorithms have only an elementary dependence on the parameter and formula. We also show that both results are easily extended from vertex cover to neighborhood diversity.Comment: Accepted for IWOCA 201