Dual system for potassium transport in Saccharomyces cerevisiae

In a newly formulated growth medium lacking Na+ and NH4+, Saccharomyces cerevisiae grew maximally at 5 microM K+. Cells grown under these conditions transported K+ with an apparent Km of 24 microM, whereas cells grown in customary high-K+ medium had a significantly higher Km (2 mM K+). The two types of transport also differed in carbonyl cyanide-m-chlorophenyl hydrazone sensitivity, response to ATP depletion, and temperature dependence. The results can be accounted for either by two transport systems or by one system operating in two different ways.

[Gynecomastia. Apropos of 122 cases]

Pathological data from 122 cases of gynecomastia are studied. According to the importance of epithelial hyperplasia and of specialised stroma, 3 types are described. Every type is compared with the age of patients, the duration of the illness and occasional etiologic circumstances. It is concluded that these 3 types are not evolutive stages, that type II is the most frequent at any age and that there is no relation between etiology and histological type, except between oestrogenic therapy and type I. The alterations of connective tissue, especially breakdown of elastic fibers, are important.

Diagnosis by ultrasonography and isotopic phlebography of a malformation of the inferior vena cava: proximal transposition with anterior crossing over the aorta

A case of a previously undescribed malformation of the inferior vena cava is reported: there was distal normoposition and proximal transposition, with anterior crossing over the aorta; the right renal vein flowed into the inferior vena cava located on the left, after crossing over the anterior face of the aorta. This anomaly was shown by echography and isotopic phlebography.

Effect of histrionicotoxin on ion channels in synaptic and conducting membranes of electroplax of Electrophorus electricus

Histrionicotoxin (HTX) at low concentrations of 5-10 microM blocks the postsynaptic potential of the electroplax of Electrophorus electricus. At 100-fold higher concentrations, HTX blocks the directly evoked action potentials of the conducting membrane. The pH dependence of the blockade by HTX at synaptic channels is different from that at the conducting membrane. At the synapse HTX is more potent at acid pH, while at the conducting membrane it is more potent at basic pH. HTX at high concentrations antagonizes the effects of batrachotoxin, indicative of an effect on the batrachotoxin-sensitive sodium channels involved in action potential generation. While the effects of HTX on the synaptic channels are concentration, time, and pH dependent, the effects on the channels of the conducting membrane are, in addition, use dependent, suggesting interactions of HTX with the activated forms of these channels.

Template Bleeding Time (TBT): Influence of Venostasis and Direction of Incision Upon the Influence of Aspirin (ASA)

It is commonly assumed that because ASA prolongs the TBT, that ASA produces hemostatic impairment. To test this assumption, we assessed the effect of two variables (incision direction and controlled venostasis) on ASA’S prolongation of the TBT in 15 normal subjects. Following the single ingestion of 10 grains of ASA, the TBT was significantly prolonged (p <. 05) up to 72 hrs. only if venostasis at 40mm Hg was maintained and the incision made parallel to the skin creases (SC). If venostasis was maintained and the incision was perpendicular to SC, significant TBT prolongation induced by ASA occurred only up to 24 hrs. TBT’s done without venostasis and with an incision perpendicular to SC never significantly differed from baseline. Collagen-induced aggregation and release of serotonin after ASA ingestion returned to normal first (13 of 15 individuals). Normalization for collagen occurred between 48 and 120 hrs. Epinephrine and then ADP recovery occurred later (up to 216 hrs.). These data suggest that ASA’s effect on TBT, aggregation and release can be exaggerated by laboratory techniques and that ASA’s effect on hemostasis may be minimal in the normal subject.

Fatty acid synthetase complex from the insect Ceratitis capitata

Fatty acid synthesis capacity of the insect Ceratitis capitata has been investigated in vitro from [1-14C]acetyl-CoA using homogenates at different stages of development. A maximum activity was observed after 5--6 days of larval development. But homogenates of the pharate adult insect did not show synthetic capacity of fatty acids. Fatty acid synthetase complex has been isolated from the particle-free supernatant fraction of homogenates from the 6-day C. capitata larvae. The enzyme complex was purified 182-fold with respect to the protein contained in the crude extract. The complex was homogeneous when analysed by gel filtration and by polyacrylamide-gel electrophoresis. The molecular weight was 5.2X10(5). The enzyme was dissociated into half-molecular subunits. Amino acid analysis, general properties, stability and kinetic constants (V and Km) for the substrates are reported. The fatty acid synthetase complex from the insect contains 42+/-1-SH residues and one phosphopatetheine moiety per 5.2X10(5). Activity was dependent on the presence of NADPH; FMN strongly inhibited the enzyme activity promoted by NADPH. The enzyme complex synthesized a range of fatty acid (10:0--18:0), palmitate being the predominant end product. The proportions of fatty acids synthesized varied with substrate concentrations. Fatty acids released from the complex were almost completely in the free form.

Compulsory regime and control of environment in animal behaviour. II. Light level preferences of carnivores

Abstract

Thirteen individuals belonging to the carnivore species Bassariscus astittus, Genetta genetta, Mustela frenata, Mustela rixosa, Tayra barbara, and Urocyon cinereoargenteus were studied in activity-wheel enclosures in which they could control the intensity of ambient illumination in 10 steps by instrumental means. The light levels available ranged from darkness to a brightest value of 150, 300, 500, or 950 lux. The acivity indices determined at each level were: time spent running (active time) and not running (inactive time), running speed, visit lengths during activity, and number of visits. Twelve of the animals preferred the brightest or second-brightest light available. The thirteenth, a genet, had not adapted to the experimental situation after 47 days of study and spent most of the time in dim light or darkness. Active time, lengths of visits, and number of visits gave essentially the same indications of light preferences during activity, with the first two indices giving the greatest resolution. Running speed showed no noteworthy correlation with light level. Plots of the ratios of both active time and visit lengths at the brightest level to those at the second brightest appear to fall into species-specific groupings that do not correlate with body size or species affinity. There were mild to notable shifts in light level preferences from activity to inactivity. In a general way the directions of the shifts are consistent with observations of the behaviour of the animals under other conditions, i.e., light-sleeping sunbathers tended to prefer brighter light during inactivity, while sound-sleeping animals that sought protective cover during the day tended to prefer dimmer light. One of the longtailed weasels consistently adjusted the lights to a dim level or darkness when disturbed daily at feeding time. During undisturbed activity, this animal preferred the brightest light available on five different programs in which switch functions, level sequences, and illuminance values were altered, in some case to markedly different arrangements. As a working hypothesis we suggest that the preference of our carnivores for light in the range of 10 to 950 lux depends on one or more aspects of their vision - such as color, contrast, pattern, and intensity discriminations - being much improved in this range compared to that in dimmer light. On the other hand, all but one of the same animals was found to be primarily or strictly nocturnal in an independent study of activity phasing. Accordingly, it appears possible that one or more of the visual discriminations mentioned above is most sought after when the animals can alternate between conditions in which he discrimination is alternately good and poor. The animals often continued to press the levers controlling the light level after the corresponding extreme level had been attained. The relative numbers of these "false steps" on the on levers and off levers suggest that, of two means available, the animals tended to seek additional environmental modification using the means (the on levers) that yielded the preferred conditions. In addition, the animals that showed the most marked preferences for bright light also were the ones with the lowest rates of "false ons", suggesting that less motivation existed to seek change from highly preferred conditions than from less preferred ones.

Roadrunners: activity of captive individuals

Two roadrunners, Geococcyx californianus, readily accepted an activity wheel as an outlet for locomotor activity. The birds were strictly diurnal and tended to be most active per unit of time in the predusk hours. There was less activity on partly overcast days than on clear days. Dim light and darkness were strongly inhibitory, even during daytime hours; bright light was stimulatory, even during nighttime hours. These findings appear to open the way for quantitative comparative studies of the influences of environmental factors on the activity of cursorial birds.