Analysis of Physarum proteins throughout the cell cycle by two-dimensional PAGE

The accumulation of several hundred proteins during the nuclear division cycle of Physarum polycephalum was measured by digital image processing of silver-stained two-dimensional (2D) polyacrylamide gels. In contrast to previous studies, we have used an organism with a naturally synchronous cell cycle, so there are no uncertainties concerning synchronization artifacts or cell-sorting artifacts, and we have measured the specific amounts of each protein rather than the rate of synthesis. Since one-dimensional SDS-PAGE shows no significant fluctuations in the most abundant plasmodial proteins, we have loaded 2D gels so that proteins of low-to-moderate abundance appear in the linear range of the silver stain standard curve. Only five proteins showed reproducible, measureable fluctuations during the cell cycle. One of these proteins was tubulin. Full quantitative information was obtained by analysing the digital images of silver-stained gels by a general image processing system.     

Identification of Tumor Antigens in the HLA Peptidome of Patient-derived Xenograft Tumors in Mouse

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Highlights

• •Sufficient tumor tissues are often unavailable large HLA peptidome discovery.
• •Using patient derived xenograft (PDX) tumors can overcome this limitation.
• •The large PDX HLA peptidomes expand significantly those of the original biopsies.
• •The HLA peptidomes of the PDX tumors included many tumor antigens.

     

Final height after growth hormone therapy in peripubertal boys with a subnormal integrated concentration of growth hormone.

The aim of this study was to test the effect of growth hormone (GH) therapy on final height in peripubertal boys with idiopathic short stature in whom a subnormal integrated concentration of GH (< 3.2 micrograms/l) was found. Twenty-eight peripubertal children were studied. Height was below 2 SD for age, growth velocity was < 4.5 cm/year, bone age was more than 2 SD below mean for age and GH response to provocative tests was more than 10 micrograms/l. Eleven subjects (group B) were treated with recombinant GH 0.75 unit/kg/week, divided into 3 weekly doses for 2 years, and then the same weekly dose divided into daily injections was administered until final height was attained. Seventeen untreated children (group A) who were followed until cessation of growth served as controls. The GH-treated patients reached their target heights (-2.1 +/- 0.5, mean +/- SD in SDS) and predicted heights (-1.8 +/- 0.8) determined by the Bayley and Pinneau method, while the final heights of the untreated patients were significantly lower than their target heights and their predicted final heights (-2.7 +/- 0.7, -1.8 +/- 1.0 and -2.7 +/- 0.7, respectively). The main effect of GH was observed during the 1st year of treatment when height velocity was significantly higher in the GH-treated group than in the untreated one (9.3 +/- 2.1 vs. 5.3 +/- 1.1, respectively, p < 0.001). The high cost of the treatment in this specific age group should be weighed against the results.     

A Hypernychthemeral Sleep-Wake Syndrome: A Treatment Attempt

The wake and sleep-onset times of a patient with a sleep-wake cycle longer than 24 hr were recorded by the patient for 4 years. During this time, the patient found himself unable to maintain a 24-hr sleep-wake schedule. When treated with 1-2 mg clonazepam, taken nightly, he was able to become entrained to a 24-hr day. Despite entrainment of his sleep-wake cycle, the patient reported depression, lack of motivation and fatigue and chose not to continue taking the drug.     

Regression analysis of the spontaneous spike activity of neurons in snail ganglia

Regression analysis of the spontaneous spike activity of neurons in Helix pomatia was carried out with the aim to establish the statistical parameters of this activity under constant experimental conditions and during longer time intervals. The activity of 38 randomly chosen neurons in visceral and parietal ganglia, penetrated by microelectrodes and activated either endogenously by pacemaker potentials or by synaptic inputs, was recorded during time intervals lasting from 20 min to 3 h. The main results of the statistical analyses are presented in the table where the parameters of both cell types are listed. The validity of the regression analysis applied here is discussed from the point of the possibility it offers for carrying on the data processing quickly and without applying complex calculating means. The results are also considered regarding the current interest of our research group.     

Intergeneric transformation betweenRhizobium andAzotobacter

Attempts were made to transform two strains ofAzotobacter, viz.A. chroococcum andA. vinelandii with the DNA ofRhizobium leguminosarum, R. japonicum, R. meliloti andR. trifoli. Resistance to streptomycin or crystal violet was used as marker for screening purposes. The frequency of transformation varied between 0.05 to 0.95 percent. The transformants also acquired a few other characters of the donor strains.     

Ecological and evolutionary consequences of selective interspecific information use

Recent work has shown that animals frequently use social information from individuals of their own species as well as from other species; however, the ecological and evolutionary consequences of this social information use remain poorly understood. Additionally, information users may be selective in their social information use, deciding from whom and how to use information, but this has been overlooked in an interspecific context. In particular, the intentional decision to reject a behaviour observed via social information has received less attention, although recent work has indicated its presence in various taxa. Based on existing literature, we explore in which circumstances selective interspecific information use may lead to different ecological and coevolutionary outcomes between two species, such as explaining observed co-occurrences of putative competitors. The initial ecological differences and the balance between the costs of competition and the benefits of social information use potentially determine whether selection may lead to trait divergence, convergence or coevolutionary arms race between two species. We propose that selective social information use, including adoption and rejection of behaviours, may have far-reaching fitness consequences, potentially leading to community-level eco-evolutionary outcomes. We argue that these consequences of selective interspecific information use may be much more widespread than has thus far been considered.     

Bacterial bioluminescence as an early indication of marine fish spoilage

Summary The relationships between different microbiological and biochemical parameters and the development of bacterial luminescence associated with the spoilage of marine fish from the Mediterranean-Sea was studied during storage at different temperatures. The bioluminescence level of the bacterial suspensions that were taken from the fish skin increased during the storage; at 20°–25°C the growth and luminescence of the luminuous bacteria correlated well with the total bacterial count while at 5°C the bacterial proliferation was not accompanied by a parallel increase in luminescence.The shift in storage temperature from 25°C to 5°C stabilized the level of the luminescence of bacterial suspension taken from the winter fish which were comprised mainly by Photobacterium phosphoreum, and caused a drop in the luminescence of bacterial suspension taken from the fish caught in the summer which were comprised mainly by Beneckea barveyi. The increase in the bioluminescence level appeared earlier than the increase in trimethylamine level and occured approximately at the same time as the increase in the hypoxanthine concentration. The potential value of the use of bacterial bioluminescence as an early indication for marine fish spoilage is discussed.     

A rapid method for the determination of microbial biomass by dry weight using a moisture analyser with an infrared heating source and an analytical balance

Aims: Microbial biomass is an important biotechnological parameter. The traditional method for its determination involves an oven‐drying step and equilibration to room temperature before weighing, and it is tedious and time consuming. This work studied the utilisation of a moisture analyser consisting of an efficient infrared‐heating module and an analytical balance for the determination of microbial biomass by dry weight. Methods and Results: The method duration depended on the sample volume and was between 7 and 40 min for sample volumes of 1–10 ml. The method precision depended on the total dry weight analysed – 10 mg of total dry weight being sufficient to achieve coefficients of variation of 5% or less. Comparison with the conventional oven method provided a correlation coefficient r² of 0·99. The recovery of an internal standard ranged between 94·2 and 106·4% with a precision of 1·39–4·53%CV. Conclusions: Validation revealed sufficient method accuracy, precision and robustness and was successfully applied to the study of yeast and bacterial growth kinetics. Techniques are discussed that allow for increased method precision at low biomass concentrations, and equations are provided to estimate required drying time and method precision based on sample volume and total sample dry weight, respectively. Significance and Impact of the Study: This work presents a rapid method for the determination of microbial biomass, allowing for the timely implementation of biomass‐based information in biotechnological and laboratory protocols.