Improved performance of anaerobic digestion ofSpirulina maxima algal biomass by addition of carbon-rich wastes

Mixtures of carbon-rich wastes andS. maxima algal biomass increase markedly the performance of anaerobic digestion. A mixture of 507 sewage sludge and algae increases the methane yield and the productivity over twofold. Peat hydrolyzate and sewage sludge, when added to algae, have shown a synergistic effect and spent sulfite liquor added at concentrations over 307 V/V has inhibited methanogenic activity.     

Increased spontaneous mutation and alkylation sensitivity of Escherichia coli strains lacking the ogt O6-methylguanine DNA repair methyltransferase.

Escherichia coli expresses two DNA repair methyltransferases (MTases) that repair the mutagenic O6-methylguanine (O6MeG) and O4-methylthymine (O4MeT) DNA lesions; one is the product of the inducible ada gene, and here we confirm that the other is the product of the constitutive ogt gene. We have generated various ogt disruption mutants. Double mutants (ada ogt) do not express any O6MeG/O4MeT DNA MTases, indicating that Ada and Ogt are probably the only two O6MeG/O4MeT DNA MTases in E. coli. ogt mutants were more sensitive to alkylation-induced mutation, and mutants arose linearly with dose, unlike ogt+ cells, which had a threshold dose below which no mutants accumulated; this ogt(+)-dependent threshold was seen in both ada+ and ada strains. ogt mutants were also more sensitive to alkylation-induced killing (in an ada background), and overexpression of the Ogt MTase from a plasmid provided ada, but not ada+, cells with increased resistance to killing by alkylating agents. The induction of the adaptive response was normal in ogt mutants. We infer from these results that the Ogt MTase prevents mutagenesis by low levels of alkylating agents and that, in ada cells, the Ogt MTase also protects cells from killing by alkylating agents. We also found that ada ogt E. coli had a higher rate of spontaneous mutation than wild-type, ada, and ogt cells and that this increased mutation occurred in nondividing cells. We infer that there is an endogenous source of O6MeG or O4MeT DNA damage in E. coli that is prevalent in nondividing cells.     

Central peptidergic mechanisms controlling reproductive hormone secretion: novel methodology reveals a role for the natriuretic peptides.

A variety of neural factors can influence reproductive hormone secretion by neuromodulatory actions within the hypothalamus or neuroendocrine actions within the anterior pituitary gland. Passive immunoneutralization and antagonist administration protocols have suggested physiological roles for a number of these factors; however, both experimental approaches have severe technical limitations. We have developed novel methodology utilizing cytotoxin cell targeting with neuropeptides linked to the toxic A chain of the plant cytotoxin ricin. With this methodology we can target and destroy in vivo or in vitro cells bearing receptors for that peptide. Ricin A chain conjugated to atrial natriuretic peptide (ANP), a neuropeptide known to pharmacologically inhibit luteinizing hormone-releasing hormone (LHRH) release, was injected into the cerebroventricular system of intact, cycling rats and ovariectomized rats. Cytotoxin conjugate treatment significantly lengthened the estrous cycle. In ovariectomized rats the luteinizing hormone surge induced by steroid priming was completely inhibited. LHRH content of the median eminences of these rats was not significantly altered. These data suggest that ANP binding to clearance receptors in the hypothalamus displaces the C-type natriuretic peptide (CNP) from the shared clearance receptor, making more CNP available to inhibit LHRH release. In the absence of cells bearing the clearance receptor all available CNP binds to the ANPR-B receptor and exerts its effect via an inhibitory interneuron, since LHRH fibers are spared by this treatment.     

Chemotaxonomy of the genus Talaromyces

Species of the ascomycetous genus Talaromyces have been examined for profiles of secondary metabolites on TLC. The greatest number of specific metabolites were produced on oatmeal-, malt extract- and yeast-extract sucrose agars. Profiles of intracellular secondary metabolites produced on oatmeal agar were specific for each species and provided a means of simple differentiation of the taxa. Examination of the most important species using high performence liquid chromatography (HPLC) allowed to solve some taxonomic problems. Known mycotoxins are produced by T. stipitatus (duclauxin, talaromycins, botryodiploidin), T. stipitatus chemotype II (emodin), T. panasenkoi (spiculisporic acid), T. trachyspermus (spiculisporic acid), T. trac macrosporus (duclauxin) and T. wortmannii (rugulosin). Wortmannin is produced by an atypical strain of T. flavus but not T. wortmannii. Several other secondary metabolites were discovered for the first time in the following species: Glauconic acid is produced by T. panasenkoi, T. ohiensis and T. trachyspermus; vermiculine by T. ohiensis; duclauxin by T. flavus var. macrosporus and the mitorubrins by T. flavus and T. udagawae. The profiles of secondary metabolites support the established taxonomy of the species based on morphology, showing the genetic stability of profiles of secondary metabolites in Talaromyces. Two new taxa are proposed: T. macrosporus comb. nov. (stat. anam. Penicillium macrosporum stat. nov.), and Penicillium vonarxii, sp. nov. for the anamorph of T. luteus.     

Inhibition of Axoplasmic Transport in the Optic System by Kainic Acid

Axoplasmic transport along the optic axons was studied after intraocular injections of kainic acid (KA). Transport of labeled material did not initiate from the eye when KA was injected simultaneously with the protein precursor [3H]proline. When KA was injected after axoplasmic transport of labeled proteins had begun, no additional radioactive material moved out of the retinal ganglion cells. However, the labeled material already present in the optic nerve at the time of KA injection continued to move, and accumulated at the nerve endings. Although KA reduces the incorporation of precursor, this effect of KA on axoplasmic transport appears to be more than a consequence of inhibition on precursor uptake or protein synthesis. Recovery from this KA action began 6 h after exposure to KA and was about 50% recovered by 36 h. The extent of the recovery remained at this level for as long as a week, which suggested a partial recovery of the ganglion cells. A second exposure to KA after the inner plexiform layer had virtually disappeared was as effective as the first exposure in preventing the appearance of transported protein in the optic nerve, suggesting a direct action of KA on the ganglion cells. We interpreted the results to indicate that KA interferes with the initiation phase of axoplasmic transport in ganglion cells and this effect is partially reversible.     

Effect of the adaptive response on the induction of the SOS pathway in E. coli K-12

Summary The adaptive-response is an inducible repair system of E. coli which reduces the mutagenic and cytotoxic effects of alkylation damage (Samson and Cairns, 1977). In adapted cells (cells exposed to sublethal doses of alkylating agents) the induction of W-reactivation and W-mutagenesis by alkylating agents is almost totally blocked. Despite the fact that adaptation has no detectable effect on UV mutagenesis in E. coli K-12, it does inhibit to some extent the UV and tif-1 mediated induction of SOS functions such as W-reactivation and prophage induction. Furthermore, the kinetics of induction of W-mutagenesis following UV treatment are altered by adaptation. In this case the adaptive-response seems to specifically block the induction of an error-producing W-reactivating capacity which normally would increase soon after UV treatment, while affecting error-free W-reactivating systems to a lesser extent.     

Protein synthesis requirement for maturation promoting factor (MPF) initiation of meiotic maturation in Rana oocytes.

Mechanisms controlling disintegration or breakdown of the germinal vesicle (GVBD) in Rana oocytes were investigated. A secondary cytoplasmic maturation promoting factor (MPF), produced in response to steroid stimulation, was shown to induce maturation when injected into immature recipient oocytes. Exposure of immature Rana oocytes to cycloheximide following injection of MPF or steroid treatment completely inhibited such maturation. Results indicate that injected MPF required protein synthesis for germinal vesicle breakdown and thus acted at some translational level. These results contrast with data obtained in Xenopus oocytes where injected MPF induced maturation in the presence of cycloheximide. Cytoplasmic MPF was also produced in Rana oocytes following treatment with lanthanum salts. This activity was similarly inhibited by cycloheximide. Time course studies conducted to compare the onset of cycloheximide insensitivity in steroid-treated and MPF-injected oocytes demonstrated that MPF-injected oocytes become insensitive to cycloheximide prior to steroid-treated germ cells. These results suggest that MPF acts as an intermediary in progesterone-induced maturation. Insensitivity to cycloheximide occurred several hours prior to the onset of germinal vesicle breakdown in both MPF-injected and steroid-treated oocytes. The data indicate that injected MPF in Rana does not induce nuclear disintegration directly, but rather requires amplification and/or autocatalytic synthesis of additional MPF or other factors for maturation to be induced. Molecular mechanisms involved in nuclear disintegration are discussed in relation to these species differences.     

Liver as a source of transformed cell growth factor

Isolated rat hepatocytes release an acidic glycoprotein(s) that can selectively promote the growth of transformed cells. This factor has a molecular weight of 60 000–70 000 D. Liver microsomal and cytosol fractions contain two species of stimulatory activity—44 000 and 3 500 D. Mitochondrial and nuclear fractions contain only the lower molecular weight factor.     

Evidence for gene inactivation in the virus-induced aberrant ratio phenomenon in maize

Reciprocal crosses were made between pairs of plants showing the "aberrant ratio" (AR) effect at the a locus, and simultaneously between these plants and an aa tester. The results suggested that the AR effect in the particular line that was used could be explained by inactivation of a gene other than A, but also required for aleurone color. Segregation ratios in additional crosses largely fit expectations predicted on the basis of this hypothesis.