Enhanced nisin and pediocin production on whey supplemented with different nitrogen sources

Production of nisin and pediocin were followed, respectively, in Lactococcus lactis subsp. lactis CECT 539 and Pediococcus acidilactici NRRL B-5627 grown with lactose and four different nitrogen sources. Neither NH₄Cl nor glycine improved production of the bacteriocins. Both yeast extract and Casitone increased pediocin production from 55 BU ml^–1 to 195 BU ml^–1 and 185 BU ml^–1, respectively. Nisin increased from 21 BU ml^–1 to 74 BU ml^–1 and 59 BU ml^–1 with these nitrogen sources.     

The Granular Chloride Channel ClC-3 Is Permissive for Insulin Secretion

Insulin secretion from pancreatic β cells is dependent on maturation and acidification of the secretory granule, processes necessary for prohormone convertase cleavage of proinsulin. Previous studies in isolated β cells revealed that acidification may be dependent on the granule membrane chloride channel ClC-3, in a step permissive for a regulated secretory response. In this study, immuno-EM of β cells revealed colocalization of ClC-3 and insulin on secretory granules. Clcn3^−/− mice as well as isolated islets demonstrate impaired insulin secretion; Clcn3^−/− β cells are defective in regulated insulin exocytosis and granular acidification. Increased amounts of proinsulin were found in the majority of secretory granules in the Clcn3^−/− mice, while in Clcn3^+/+ cells, proinsulin was confined to the immature secretory granules. These results demonstrate that in pancreatic β cells, chloride channels, specifically ClC-3, are localized on insulin granules and play a role in insulin processing as well as insulin secretion through regulation of granular acidification.     

Genetic Analysis and Species Specific Amplification of the Artemisinin Resistance-Associated Kelch Propeller Domain in P. falciparum and P. vivax

Plasmodium falciparum resistance to artemisinin has emerged in the Greater Mekong Subregion and now poses a threat to malaria control and prevention. Recent work has identified mutations in the kelch propeller domain of the P. falciparum K13 gene to be associated artemisinin resistance as defined by delayed parasite clearance and ex vivo ring stage survival assays. Species specific primers for the two most prevalent human malaria species, P. falciparum and P. vivax, were designed and tested on multiple parasite isolates including human, rodent, and non- humans primate Plasmodium species. The new protocol described here using the species specific primers only amplified their respective species, P. falciparum and P. vivax, and did not cross react with any of the other human malaria Plasmodium species. We provide an improved species specific PCR and sequencing protocol that could be effectively used in areas where both P. falciparum and P. vivax are circulating. To design this improved protocol, the kelch gene was analyzed and compared among different species of Plasmodium. The kelch propeller domain was found to be highly conserved across the mammalian Plasmodium species.     

Expression of beta-amyloid precursor protein in reactive astrocytes following neuronal damage

Although the beta-amyloid peptide is an established core component of neuritic plaques that accumulate in Alzheimer's disease, the mechanisms responsible for its deposition are not well understood. We now report that lesions of rat hippocampal neurons cause a time-dependent, long-lasting elevation of immunoreactivity for the beta-amyloid precursor protein (APP) in neighboring astrocytes, a cell type not normally containing the protein. The increase represents astroglial expression of the protein rather than a scavenging of APP released by damaged neurons. Immunoelectron microscopy confirmed that APP-containing cells are reactive astroglia, both surrounding capillaries and within the neuropil. These results demonstrate that neuronal damage stimulates APP expression in adult brain and suggest that reactive astrocytes may be a source of the beta-amyloid that forms neuropathological plaques in Alzheimer's disease.     

Regulation of axonemal Mg2+-ATPase from Paramecium cilia: effects of Ca2+ and cyclic nucleotides

Ciliary activity is regulated by Ca2+ and cyclic nucleotides, but the molecular mechanisms of the regulation are unknown. We have tested the ability of Ca2+ and cyclic nucleotides to alter ciliary Mg2+-ATPase or to stimulate phosphorylation of axonemal dynein. Mg2+-ATPase activity in cilia and axonemes from Paramecium was stimulated 2-fold by micromolar Ca2+, but this Ca2+ sensitivity was lost upon solubilization of the dyneins from the axoneme. The Ca2+-sensitive component of ciliary Mg2+-ATPase activity was inhibited by the dynein inhibitors vanadate and Zn2+, but was insensitive to the calmodulin antagonists calmidazolium and melittin. Dynein activity in the high-salt extract from axonemes was also insensitive to calmidazolium. Calmodulin did not sediment with 22 S or 12 S dyneins on sucrose gradients containing Ca2+, but it did sediment in the region from 19 S to 14 S. Mg2+-ATPase activity in ciliary fractions was unaltered in the presence of cAMP or cGMP. However, polypeptides associated with the 22 S and 12 S dyneins, as well as proteins of 19 S, 15 S, and 8 S, were substrates for endogenous ciliary kinases. High molecular weight polypeptides that sedimented at 22 S and 19 S were phosphorylated in a cyclic nucleotide-stimulated manner.     

Rapid Copper Acquisition by Developing Murine Mesothelioma: Decreasing Bioavailable Copper Slows Tumor Growth,Normalizes Vessels and Promotes T Cell Infiltration

Copper, an essential trace element acquired through nutrition, is an important co-factor for pro-angiogenic factors including vascular endothelial growth factor (VEGF). Decreasing bioavailable copper has been used as an anti-angiogenic and anti-cancer strategy with promising results. However, the role of copper and its potential as a therapy in mesothelioma is not yet well understood. Therefore, we monitored copper levels in progressing murine mesothelioma tumors and analyzed the effects of lowering bioavailable copper. Copper levels in tumors and organs were assayed using atomic absorption spectrophotometry. Mesothelioma tumors rapidly sequestered copper at early stages of development, the copper was then dispersed throughout growing tumor tissues. These data imply that copper uptake may play an important role in early tumor development. Lowering bioavailable copper using the copper chelators, penicillamine, trientine or tetrathiomolybdate, slowed in vivo mesothelioma growth but did not provide any cures similar to using cisplatin chemotherapy or anti-VEGF receptor antibody therapy. The impact of copper lowering on tumor blood vessels and tumor infiltrating T cells was measured using flow cytometry and confocal microscopy. Copper lowering was associated with reduced tumor vessel diameter, reduced endothelial cell proliferation (reduced Ki67 expression) and lower surface ICAM/CD54 expression implying reduced endothelial cell activation, in a process similar to endothelial normalization. Copper lowering was also associated with a CD4⁺ T cell infiltrate. In conclusion, these data suggest copper lowering is a potentially useful anti-mesothelioma treatment strategy that slows tumor growth to provide a window of opportunity for inclusion of other treatment modalities to improve patient outcomes.     

Effects of Brassica oleracea waxblooms on predation and attachment by Hippodamia convergens

Four mutations that reduce waxbloom in Brassica oleracea L. were examined for their effects on predation, mobility, and adhesion to the plant surface by the general predator Hippodamia convergens (Guérin-Menéville) (Coleoptera: Coccinellidae). The mutations reduce waxbloom to different degrees, but all produce a glossy phenotype. Plants tested were inbred lines, near isogenic lines, or segregating F₂ populations, depending on the mutation. In an experiment on caged leaves, predation of Plutella xylostella L. larvae by H. convergens adult females was significantly greater on glossy types as compared with normal-wax or wild-type counterparts. Although the trend was the same for each mutation, individual comparisons between glossy and normal-wax lines or segregants were only significant for two of them, those producing mutant alleles gl_a and gl_d. Individual H. convergens were observed to spend more time walking on leaf edges and less time walking on leaf surfaces of normal-wax plants than glossy plants. Hippodamia convergens also obtained better adhesion to the surfaces of glossy plants than to normal-wax plants when tested using a centrifugal device. Two of the mutations produced similarly strong effects on predation, behaviour, and adhesion by H. convergens. These two are the same previously determined by us to provide the strongest similar effects on another generalist predator, Chrysoperla plorabunda (Fitch). The results indicate that waxbloom variation in nature could affect herbivore populations through its effects on generalist predators.