Polarized absorption picosecond kinetics as a probe of energy transfer in phycobilisomes of Synechococcus 6301

The energy transfer between C-phycocyanin chromophores in intact phycobilisomes of Synechococcus 6301 is shown to lead to an anisotropy relaxation with a lifetime of 10 ± 2 ps. However, due to the molecular order within the hexameric units of C-phycocyanin the anisotropy does not decay to zero. The Förster dipole-dipole mechanism of energy transfer can qualitatively explain these data provided that there is no back transfer of excitation energy and that the chromophore distribution is non-random. The rate of energy transfer in phycobilisomes between C-phycocyanin and allophycocyanin can best be described by a double exponential with lifetimes of 12 ± 3 and 84 ± 8 ps.     

Physical mapping and characterization of the mitochondrial DNA and RNA sequences from mit- mutants defective in cytochrome oxidase peptide 1 (OXI 3).

Summary The striking similarity between the treatments that induce SOS functions and those that result in stable DNA replication (continuous DNA replication in the absence of protein synthesis) prompted us to examine the possibility of stable DNA replication being a recA ⁺ lexA ⁺-dependent SOS function. In addition to the treatments previously reported, ultraviolet (UV) irradiation or treatment with mitomycin C was also found to induce stable DNA replication.The thermal treatment of tif-1 strains did not result in detectable levels of stable DNA replication, but nalidixic acid readily induced the activity in these strains. The induction of stable DNA replication with nalidixic acid was severely suppressed in tif-1 lexA mutant strains. The inhibitory activity of lexA3 was negated by the presence of the spr-51 mutation, an intragenic suppressor of lexA3.Induced stable DNA replication was found to be considerably more resistant to UV irradiation than nromal replication both in a uvrA6 strain and a uvr ⁺ strain. The UV-resistant replication occurred mostly in the semiconservative manner. The possible roles of stable DNA replication in repair of damaged DNA are discussed.     

Laccase in Anacardiaceae

The presence of a typical laccase is demonstrated in the cavities of the secretory ducts of a number of species of the Anacardiaceae, including Mangifera indica and Schinus molle. In addition mango fruit contains catechol oxidase. The presence of laccase may be of chemotaxonomic value.     

Proline metabolism in isolated rat liver cells

The metabolism of proline was studied in liver cells isolated from starved rats. The following observations were made. 1. Consumption of proline could be largely accounted for by production of glucose, urea, glutamate and glutamine. 2. At least 50% of the total consumption of oxygen was used for proline catabolism. 3. Ureogenesis and gluconeogenesis from proline could be stimulated by partial uncoupling of oxidative phosphorylation. 4. Addition of ethanol had little effect on either proline uptake or oxygen consumption, but strongly inhibited the production of both urea and glucose and caused further accumulation of glutamate and lactate. Accumulation of glutamine was not affected by ethanol. 5. The effects of ethanol could be overcome by partial uncoupling of oxidative phosphorylation. 6. The apparent K_m values of argininosuccinate synthetase (EC 6.3.4.5) for aspartate and citrulline in the intact hepatocyte are higher than those reported for the isolated enzyme. 7. 3-Mercaptopicolinate, an inhibitor of phosphoenolpyruvate carboxykinase (EC 4.1.1.32), greatly enhanced cytosolic aspartate accumulation during proline metabolism, but inhibited urea synthesis. 8. It is concluded that when proline is provided as a source of nitrogen to liver cells, production of ammonia by oxidative deamination of glutamate is inhibited by the highly reduced state of the nicotinamide nucleotides within the mitochondria. 9. Conversion of proline into glucose and urea is a net-energy-yielding process, and the high state of reduction of the nicotinamide nucleotides is presumably maintained by a high phosphorylation potential. Thus when proline is present as sole substrate, the further oxidation of glutamate by glutamate dehydrogenase (EC 1.4.1.3) is limited by the rate of energy expenditure of the cell.     

Studies on secretory glycoproteins in the rat exocrine pancreas

Summary A fetuin, fucosyl transferase has been identified in the smooth microsomal fraction from the rat exocrine pancreas. This enzyme is involved in the glycosylation of secretory proteins and is bound to membranes, predominantly of the Golgi complex. Optimal in vitro conditions for the assay of the enzyme activity were established: a pH of 5.5–6.0, a temperature of 21° C and concentrations of Mg^{+ +} at 5.0 mM and ATP at 2.0 mM.Supported by a grant from the Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg (Ke 113/10). Dedicated to Professor Helmut Ferner, Vienna, on the occasion of his 65^th birthday.     

Purification and properties of laccase from Botrytis cinerea

The partial purification of an extracellular laccase from Botrytis cinerea is described. Specificity of the enzyme, its K_m for a number of substrates and sensitivity to some inhibitors are described. The enzyme is a typical laccase but has an exceptionally low pI and great stability to acid pH. On gel electrophoresis two isoenzymes could be detected.     

A preliminary field investigation of the yellow handed titi monkey,Callicebus torquatus torquatus,in Northern Peru

A three month field study was conducted onCallicebus torquatus near the Nanay River in northern Peru. Data were collected primarily by the time sampling method. Information on daily movement, vocalizations, population density, and social behavior is presented. The titi monkeys we studied have a family unit pattern of social organization, territoriality accompanied by vocal activity, and a home range of about 20 hectares. There is a high degree of parental investment in care of the infant on the part of the adult male. A preliminary version of this paper was presented at the 73rd Annual meeting, American Anthropological Association, Mexico City, November, 1974.     

Viscosity and potentiometric measurements of poly(L-histidyl-L-alanyl-α-L-glutamic acid) and poly(L-lysyl-L-alanyl-α-L-glutamic acid)

Poly(His-Ala-Glu) and poly(Lys-Ala-Glu) were examined by viscosity and potentiometric titration. These measurements were interpreted in terms of the hydrodynamic size of the above sequential polypeptides. Effects of polymer, size and concentration, and solution-salt concentration were demonstrated. Although the sequential polypeptides generally behave like polyampholytes, they do demonstrate some differences. These differences my be attributed to the ability of ionized side chains three residues apart to repel themselves, in the order His < Glu < Lys.     

Evidence for the regulation of pyridoxal 5′-phosphate formation in liver by pyridoxamine (pyridoxine) 5′-phosphate oxidase

Pyridoxamine (pyridoxine) 5′-phosphate oxidase (EC 1.4.3.5) purified from rabbit liver is competitively inhibited by the reaction product, pyridoxal 5′-phosphate. The K_i, 3 μM, is considerably lower than the K_m for either natural substrate (18 and 24 μM for pyridoxamine 5′-phosphate and 25 and 16 μM for pyridoxine 5′-phosphate in 0.2 M potassium phosphate at pH 8 and 7, respectively). The K_i determined using a 10% rabbit liver homogenate is the same as that for the pure enzyme; hence, product inhibition $\text{in}\text{vivo}$ is probably not diminished significantly by other cellular components. Similar determinations for a 10% rat liver homogenate also show strong inhibition by pyridoxal 5′-phosphate. Since the reported liver content of free or loosely bound pyridoxal 5′-phosphate is greater than K_i, the oxidase in liver is probably associated with pyridoxal 5′-phosphate. These results also suggest that product inhibition of pyridoxamine-P oxidase may regulate the $\text{in}\text{vivo}$ rate of pyridoxal 5′-phosphate formation.     

Self-care in rural areas of India and Nepal

Self-care during illness and pregnancies by individuals and their families is a ubiquitous and integral part of societies throughout the world. This paper reports findings about self-care practices identified during four studies carried out over a ten-year period involving about 14,000 interviews in 7,400 households comprising over 48,000 people in three Indian states and three districts of Nepal. The proportion of ill individuals using self-care over a two-week period in the different study areas ranged from 19 to 42 percent. This involved 5 to 9 percent of the total population in self-care activities during these two weeks. Much larger differences were found between India and Nepal in the use of self-care during pregnancies. Self-care or care by relatives and friends was the predominant source of maternity care in Nepal, including deliveries, while Indian maternal care was dominated by traditional birth attendants. Comparisons also were made between self-care and the use of professional healers or health care services during the same time period. Differences in the use of self-care by age, sex, caste, access to government or special project services, type of illness, and duration and severity of illness have also been shown. The need for similar, better standardized surveys in combination with intensive studies examining the details and rationale behind self-care practices in different societies has been stressed as an essential step in developing programs to expand or modify self-care practices of individuals and their families.Portions of this paper were presented at the CPHA/WFPHA Annual Meetings and International Congress on Primary Health Care — A Global Perspective, Halifax, Nova Scotia, Canada, May 23–26, 1978. It is based on projects supported by the following institutions or agencies: India - Indian Council of Medical Research, Directorates of Health and Family Planning — Punjab and Karnataka, and the Agency for International Development (U.S.); and Nepal: Institute of Medicine (Nepal) and the International Development Research Centre (Canada).