Insulin and fructose regulate malic enzyme activity by different processes

A comparison of the regulatory processes controlling hepatic malic enzyme activity following treatment of diabetic rats with insulin or with a high fructose diet demonstrated several important differences. Insulin treatment caused a 50-fold increase in activity, due to a 12-fold increase in enzyme quantity and a 4-fold increase in specific activity(units/nmol). Dietary fructose caused a 3-fold increase in enzyme activity, due to a 3-fold increase in enzyme quantity, with no change in the specific activity of the enzyme. Thus, while fructose initiated a minor increase in malic enzyme activity, insulin was more effective, causing a substantially greater increase in enzyme activity and activating a hormone specific alteration in the catalytic activity of each enzyme molecule.     

Degradation of HeLa S3 cell chromatin by auromomycin and its chromophore

The antitumor protein agent auromomycin was found to degrade chromatin structure primarily by inducing strand scissions in linker regions. The reaction was stimulated by dithiothreitol. The chromophore form of the drug caused similar effects on chromatin, but it appeared to function at a more rapid rate. There was no evidence that auromomycin could cause breakage in core regions of chromatin.     

Worldwide distribution of commercial resources of seaweeds including Gelidium

The commercial exploitation of seaweeds for use as food and for the production of agar, alginate and carrageenan is outlined. The quantities of seaweed harvested for each purpose are tabulated and discussed. Seaweeds for food are derived chiefly from China, Japan and Korea, with almost 94% obtained by cultivation. Alginophytes are collected in 15 countries but six of these account for more than 80% of the total harvest; all are from natural stocks except for a large quantity of Laminaria cultivated in China. Natural carrageenophytes, from 12 countries, now account for only 20% of the total harvest; the remainder is cultivated Eucheuma species, 99% of which is produced in only two countries, the Philippines and Indonesia. Of the four categories of commercial resources of seaweeds considered, agarophytes are spread more evenly over a greater number of countries; they come from 20 countries and only five of these are minor contributors to the total. Gelidium species are particularly important because of the high quality agar they yield; their distribution and location are discussed.     

Interaction of guanine nucleotides with adenylate cyclase in normal and spontaneously transformed RL-RP-C cloned rat hepatocytes

Spontaneous transformation of RL-PR-C hepatocytes leads to alterations in the adenylate cyclase complex which include a lower than normal basal level of activity, a loss of sensitivity to exogenous GTP, and a decreased sensitivity to isoproterenol. Both normal and transformed membranes possess substantial GTPase activity. Treatment of transformed hepatocyte membranes with either isoproterenol plus GMP or with cholera toxin, under conditions that displace tightly bound GDP, restored the GTP effect on adenylate cyclase, and eliminated the lag in the activation by guanyl-5'-yl-imidodiphosphate. Such pretreatment also enhanced guanine nucleotide effects on the adenylate cyclase of normal hepatocytes. These results are explainable on the basis that transformation increases adenylate cyclase-associated GTPase activity, and increases occupancy of nucleotide regulatory sites by inactive or inhibitory guanine nucleotides, e.g., GDP. Seemingly, both catecholamines and cholera toxin promote an exchange reaction at the regulatory sites, resulting in clearance of these sites of inhibitory nucleotides.     

Anaerobic Granular Sludge Bioreactor Technology

Anaerobic digestion is a mature wastewater treatment technology, with worldwide application. The predominantly applied bioreactor designs, such as the upflow anaerobic sludge blanket and expanded granular sludge bed, are based on the spontaneous formation of granular sludge. Despite the exploitation of granular reactors at full-scale for more than two decades, the mechanisms of granulation are not completely understood and numerous theories have been put forward to describe the process from a biological, ecological and engineering point of view. New technological opportunities are emerging for anaerobic digestion, aided by an improved understanding of microbiological and environmental factors affecting the formation and activity of anaerobic granular sludge.