Complementation of a pKM101 derivative that decreases resistance to UV killing but increases susceptibility to mutagenesis

The drug resistance plasmid pKM101 makes Escherichia coli resistant to the lethal effects of ultraviolet (UV) irradiation and more susceptible to mutagenesis by a variety of agents. The plasmid operon responsible for increasing mutagenesis has been termed mucAB (Mutagenesis, UV and chemical). We have isolated a derivative of pKM101 called pGW1975 which makes cells more sensitive to killing by UV but which retains the ability of pKM101 to increase susceptibility to methyl methanesulfonate (MMS) mutagenesis. pGW1975 increases UV mutagenesis less than pKM101 in a uvrA⁺ strain but more than pKM101 in a uvrA⁻ strain. muc⁻ point and insertion mutants of pKM101 and pGW1975 complement to restore the plasmid-mediated: (i) ability to reactivate UV-irradiated phage, (ii) resistance to killing by UV, and (iii) level of susceptibility to UV mutagenesis. We have identified a 2.0 kb region of pKM101 which is responsible for the complementation and which maps counterclockwise of mucAB.     

Proton nuclear magnetic resonance study of N,N-diethylformamide exchange on (N,N-diethylformamide)2,2′2″-tris(dimethylamino)triethylamine)cobalt(II) and its copper(II) analogue

Proton NMR studies of N,N-diethylformamide (def) exchange on [M(Me₆tren)def]²⁺ where M = Co and Cu yield: k_ex (298.2K) = 26.3 ± 2.2, 980 ± 70 s⁻¹; ΔH^≠ = 58.3 ± 1.7, 36.3 ± 0.9 kJ mol⁻¹; ΔS^≠= −22.2 ± 4.6, −65.9 ± 2.5 J K⁻¹ mol⁻¹; and ΔV^≠ = −1.3 ± 0.2, 5.3 ± 0.3 cm³ mol⁻¹ respectively. These data which are consistent with a and d activation modes operating when M = Co and Cu respectively are compared with data for related systems.     

Wound-induced proteinase inhibitors from tomato leaves. II. The cDNA-deduced primary structure of pre-inhibitor II

A cDNA containing the complete amino acid-coding region of wound-induced tomato Inhibitor II was constructed in the plasmid pUC9. The open reading frame codes for 148 amino acids including a 25-amino acid signal sequence preceding the N-terminal lysine of the mature Inhibitor II. The Inhibitor II sequence exhibits two domains, one domain having a trypsin inhibitory site and the other a chymotrypsin inhibitory site, apparently evolved from a smaller gene by a process of gene duplication and elongation. The amino acid sequence of tomato leaf Inhibitor II exhibits homology with two small proteinase inhibitors isolated from potato tuber and an inhibitor from eggplant. The small potato tuber inhibitors are homologous with 33 amino acids of the N-terminal domain and 19 amino acids from the C-terminal domain. Two identical nucleotide sequences of Inhibitor II cDNA in the 3' noncoding region were present that were also found in an Inhibitor I cDNA. These include an atypical polyadenylation signal, AATAAG, and a 10-base palindromic sequence, CATTATAATG, for which no function is yet known.     

Regulation of endogenously catalyzed ADP-ribosylation in adipocyte plasma membranes by Ca and calmodulin

The effects of Ca²⁺ and calmodulin on endogenously catalyzed ADP-ribosylation were investigated in adipocyte plasma membranes. Four specific proteins of 70, 65, 61 and 52 kDa were labeled with [³²P]ADP-ribose and ADP-ribosylation of the proteins was highly dependent upon the conditions employed. ADP-ribosylation of the 70 kDa protein was observed only in membranes supplemented with Ca²⁺. Maximal incorporation of [³²P] into the protein was achieved with free Ca²⁺ concentrations of 90 μM. Calcium-stimulated ADP-ribosylation of the 70 kDa protein was inhibited by calmodulin. Half-maximal inhibition was observed in membranes incubated with 1.2 μM calmodulin. The effect of calmodulin was characterized by an inhibition of the incorporation of [³²P]ADP-ribose as opposed to a stimulation of its removal. ADP-ribosylation of the 61 kDa protein was not altered by added Ca²⁺ and/or calmodulin whereas ADP-ribosylation of the 65 kDa protein was partially (50%) inhibited by free Ca²⁺ concentrations between 10⁻⁶ – 10⁻⁵ M. These results provide evidence that the adipocyte plasma membrane contains ADP-ribosyltransferase activities and demonstrate that ADP-ribosylation of a 70 kDa protein is regulated by Ca²⁺ and calmodulin.     

Autoradiographic studies with fatty acids and some other lipids: A review

In this review, we have mainly included studies in which whole-body autoradiography was used. In lipid research, most studies have been done with fatty acids. These studies showed some common characteristics in the pattern of tissue distribution. A major uptake was seen in the brown fat, liver and adrenal cortex but also to some extent in other tissues with a high metabolic activity or high cell turn-over, e.g. the gastric and intestinal mucosa, diaphragm, kidney cortex and bone marrow. Low levels of radioactivity were generally found in the brain, testes, thymus, white fat, skeletal muscles, lungs and spleen. Most fatty acids showed some specific features, e.g the strong uptake of erucic, arachidonic and docosahexaenoic acid in myocardium and of eicosapentaenoic acid in the adrenal cortex. Studies with PGE1 and LTC3 showed that the liver and kidney and to a lesser degree the lungs were the major sites of metabolism. The distribution of free cholesterol and triolein emulsion labelled in the fatty acid moieties did show some similarities with respect to the general pattern found with most fatty acids. Specific for cholesterol was a very strong uptake in the adrenal cortex. There was also a significant uptake in the spleen whereas the uptake in the brown fat was not as marked as for most fatty acids. Specific for triolein was a marked uptake in the spleen and myocardium, in fed animals also in the white adipose tissue. These studies show that whole-body autoradiography can give much valuable information of the uptake and distribution of lipids that would be rather difficult to obtain with conventional methods. Combined with electron-microscopy, autoradiography can be used to study cellular and even subcellular distribution, and thus given further data on the metabolism of lipids in the body.     

On the low viscosity blood of two cold water,marine sculpins

Summary The viscosities of blood from shorthorn sculpin (Myoxocephalus scorpius), longhorn sculpin (Myoxocephalus octodecemspinosus) and winter flounder (Pseudopleuronectes americanus) were compared using a cone-plate viscometer. Both species of sculpin were almost identical with respect to blood and plasma viscosity at the temperatures (0 and 15°C) and shear rates (2.3–90/s) examined. In contrast, the viscosities of winter flounder blood and plasma were considerably greater than those observed in the sculpins. This difference in blood viscosity between the shorthorn sculpin and the winter flounder persisted over the hematocrit range of 0 to 40% red blood cells. The viscosity of the plasma and the interactions between plasma proteins and red blood cells appeared to be the major reasons for the relatively high viscosity of the flounder blood. Although a proportion of the flounder blood viscosity was attributable to fibrinogen, other plasma proteins also appeared to play a significant role. The relatively low blood viscosity of the sculpin species may confer a circulatory advantage during periods of low water temperatures.     

Hematology of three deep-sea fishes: a reflection of low metabolic rates

Blood was collected from three species of fish, Antimora rostrata (Moridae), Lycodes esmarkii (Zoarcidae), Macrurus berglax (Macrouridae), caught at depths ranging from 280 to 2300 m. Hemoglobin concentrations were low in all three species, ranging from 4.4 to 5.4 g/100 ml. Mean erythrocyte volumes were relatively large, and ranged from 277 micron3 in M. berglax to 672 micron3 in A. rostrata. Blood oxygen dissociation curves were hyperbolic, with relatively low Hill constants (0.95-1.26). Mean P50 values ranged from 10 mmHg in M. berglax to 28 mmHg in L. esmarkii. It is concluded that the hematology and oxygen-binding characteristics of the blood of these three deep-sea fish reflects adaptations to low metabolic rates and low general activity habits.     

Critical roles for juvenile hormone and its esterase+ in the prepupa of Trichoplusia ni

In the caterpillar Trichoplusia ni (Lepidoptera: Noctuidae) it has been demonstrated by allatectomy that the appearance of juvenile hormone during the prepupal stage is crucial for the successful larval-pupal ecdysis of most larvae. Application of juvenile hormone or juvenile hormone esterase inhibitors at key times disrupted normal development as well. Thus the subsequent disappearance of juvenile hormone is regulated by degradation by juvenile hormone esterase in addition to a hypothetical reduction in biosynthesis. This reduction in juvenile hormone titer in the prepupa is just as critical for normal development as was its previous appearance. These observations on the critical role of juvenile hormone in the prepupa are in contrast to observations in some other species. For instance, in the case of Manduca sexta (Lepidoptera: Sphingidae), juvenile hormone is considered only supplementary to the action of prothoracicotropic hormone in the postwandering stage and primarily is required for normal pupal development. It thus appears that even within the Lepidoptera the role of juvenile hormone in prepupal development can vary dramatically.