Cancer Cell Derived Small Extracellular Vesicles Contribute to Recipient Cell Metastasis Through Promoting HGF/c-Met Pathway,

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Highlights

• •Quantitative proteomics analysis of cancer cell derived small extracellular vesicles (sEVs) reveals metastasis related proteins.
• •HGF/c-Met signaling pathway is mainly activated by cancer cell-secreted sEVs-HGF.
• •sEVs-HGF plays essential role in the metastasis of cancer cells.

     

EPR characterization of oxide supported transition metal ions: Relevance to catalysis

EPR spectroscopy is a powerful tool to identify at a molecular level, the different steps of catalyst preparation, and of catalytic reactions:

1. Deposition of paramagnetic transition metal ions onto a support is monitored, and the coordination sphere of the metallic center is characterized by EPR.
2. The catalyst is also characterized after activation (thermal oxidation or reduction):

- the distribution among the different sites in zeolites can be determined;

- the dispersion of the active phase may be appreciated;

- the unsaturation degree of the active site may be evaluated using probe molecules such as water or¹³C enriched carbon monoxide.

1. The catalytic mechanisms can be investigated by studying the elementary steps of the catalytic reaction, as illustrated for methanol oxidation over Mo/SiO₂ catalysts whose EPR results have extended the reaction mechanism proposed on the basis of kinetic data. In addition, reaction intermediates may be isolated inquasi-in situ conditions as in the case of olefin oligomerization catalyzed by Ni/SiO₂ systems.

     

A study on the rate of water transport of the clam katelysia opima in relation to environmental conditions

1. The neutral red technique was employed to study the rate of filtration in Katelysia opima.
2. The weight specific water filtration was found to be greater for younger clams compared to the older ones.
3. The rate of water filtration increased with decreasing salinity.
4. Water filtration was found to increase as temperature increased, reaching a maximum at 35°C. but then sharply decreasing at 39°C.
5. Light had no significant effect on the rate of filtration.
6. Suspended matter was found to affect the rate of water filtration.
7. The rate of filtration was low at high pH and high in low pH.
8. The rate of water filtration was found to be faster during high tide than during low tide.
9. The presence of the parasitic crab, Pennotheris sp., in the mantle cavity of clams had a marked effect on the particle filtration.
10. Accidental cut of the siphon tips had no effect on the rate of filtration.

     

The use of toxicokinetics for the safety assessment of drugs acting in the brain

Pharmacological and toxicological studies undertaken on drugs that affect the brain are frequently performed in disparate species under various experimental conditions, at doses often greatly in excess of those expected to be administered to humans, and the findings are extrapolated implicitly or explicitly with scant regard to differences in the biodisposition of the drugs. Such considerations are necessary since:

1. Species;
2. Strain;
3. Gender;
4. Route;
5. Dose;
6. Frequency and time of administration;
7. Temperature;
8. Coadministration of drugs; and
9. Surgical manipulation

are but some of the factors that have been shown to influence the kinetics and metabolism of drugs. This article, using MDMA and other phenylethylamines as examples, provides evidence for the need to measure the exoosure of the drugs and their active metabolites in blood and brain (toxicokinetics) in order that conclusions based only on dynamic, biochemical, or histological evidence are more pertinent. Further, the combined use of toxicokinetic-dynamic modeling can lead to a better appreciation of the mechanisms involved and a more useful approach to the calculation of safety margins.     

Seasonal variation in the biochemical composition of Mytilus viridis at Ratnagiri on the West Coast of India

1. The seasonal variation in the water, protein, fat and glycogen contents of the mussel, Mytilus viridis has been studied for the year March, 1974 to March, 1975.
2. The water level increased during the monsoon season and decreased in summer.
3. The level of protein, fat and glycogen showed correlation with the reproductive cycle of the mussel.
4. The protein level was high when the mussels were mature and dropped during the breeding period.
5. During sex change from male to female in May the protein level remained high whereas during sex change from female to male in October and November it was low.
6. The fat level was high in mature mussels and declined on spawning.
7. The glycogen level was at its peak in immature mussels and low in mature.

     

Changes in cell composition and viability of Bdellovibrio bacteriovorus during starvation

1. Washed cell suspensions of Bdellovibrio bacteriovorus harvested shortly after lysis of their substrate organisms and shaken in buffer have a constant and high endogenous respiration rate for a bout 6 h which then declines sharply to a rate approximately 10% of the original. Viability of cell suspensions shows little change over the first 4–6 h and then decreases by some 50% in 10 h.
2. Over the first 5–6 h of starvation there is a loss of about 50% of total cell carbon. This loss is distributed about equally between CO₂ and small molecules released into the suspending buffer. The protein and nucleic acid contents of the cells decrease concomitantly from time zero during starvation while DNA content remains constant. Ribosomal profiles show a rapid degradation of ribosomes.
3. In the presence of glutamate or glutamate plus a balanced amino acid mixture, loss of cell material and loss of viability is partially or completely prevented. There is extensive protein turnover when glutamate and an amino acid mixture are available to the bdellovibrio.
4. The pattern of changes observed in B. bacteriovorus during starvation is compared to reported changes in other species of bacteria, and the significances of its high endogenous respiration and sensitivity to starvation are discussed.

     

Recent advances in studies of evolutionary relationships between proteins and nucleic acids

Evolution depends upon the occurrence of occasional changes, large or small, in hereditary characteristics. Molecular genetics gave rise to the new field of molecular evolution, which is currently exploring the changes that take place in proteins and nucleic acids over long periods of time. The following are some of the fundamental assumptions:

1. The phenotypic characteristics of organisms depend directly on proteins.
2. Proteins are synthesized in accordance with information carried in molecules of DNA as sequences of the four bases, adenine, guanine, cytosine, and thymine. The information is transcribed into molecules of messenger RNA and is translated into proteins by the intervention of the genetic code.
3. Changes in the composition of the base sequences in DNA can take place in living organisms, and these changes can affect the phenotypic characteristics of the next generation.
4. The process of natural selection favors the perpetuation of organisms which compete successfully in the struggle for existence. This process leads to the elimination of all but a small fraction of the astronomical number of possible protein molecules that could result from genetic translation of the possible variants of DNA. Furthermore, the number of protein molecules was originally much smaller than it is to-day, and it has increased by hereditary processes rather than by the chance appearance of entirely new proteins.
5. The DNA present in any single cell contains the complete information for all the hereditary characteristics of the organism. The amount of DNA per cell may increase during evolution and this increase has produced modern organisms that are ‘higher’, more specialized, and more complex, from carlicr and simpler forms.
6. Protein molecules are slowly and steadily differentiated during evolution if their genes are physically separated from each other, by allopatric speciation or even by duplication and translocation, whether or not the function of the proteins are changed.
7. Mutations, together with recombination, contribute to changes in the genetic pool which provide the variability within populations that is necessary for evolution of species.

The field of molecular evolution should include a theory of the chemical events leading to the formation of the first living organism from molecules of non-living origin. The gentic code may have evolved through multiplication of transfer RNA molecules by gene duplication followed by differentiation. This proposal is supported by the similarities between all tRNA molecules of known structures. The DNA of higher organisms contains families of repetitive sequences. The families may contain thousands or hundreds of thousands of individual members. The ‘family resemblance’ within each group grows less with the passage of time because this leads to differentiation resulting from the accumulation of point mutations.     

Intracellular proteolytic activity in developing myxospores of Myxococcus xanthus

1. Cell-free extracts from vegetative cells and developing myxospores of Myxococcus xanthus were found to contain similar amounts of proteolytic activity, approximately 80% of which was due to one or more neutral metal proteases.
2. Sixty per cent of the proteolytic activity was particulate.
3. The specific activity of the proteases was high throughout all stages of myxospore formation and displayed small increases in activity at two stages of development: (1) during cell shortening and (2) immediately following the conversion to spheres. The first peak in activity was apparent in assays conducted at pH 8 or 10 whereas the second peak was obvious only at pH 6.
4. A mutant which develops into myxospores only after a lag of approximately 7–8 h possessed levels of proteases similar to the wild type and displayed a peak in proteolytic activity after a delay of 7–8 h.
5. Low levels of serine protease activity were occasionally detected in both vegetative cells and myxospores; no sulfhydryl proteases were detectable in either cell type.
6. Extracellular proteases accumulated in the medium throughout myxospore development but differed from the intracellular proteases in pH optima and sensitivity to inhibitors.

     

Experimental problems using electronic particle counters

The following scheme lists the problems which have been and will continue to be encountered in grazing experiments on natural particle assemblages. In some cases there are solutions, but many of the problems listed below remain intractable. To solve them will require innovative approaches, most probably combining the use of particle counters with other techniques to approach the problem to be solved from several angles at once. Variance between samples due to

- statistical causes (especially caused by large particles) and

- differences between experimental bottles and between experimentals and controls at start of experiment. Shifts in particle distribution during experiment due to

- increase in small particles

- growth of bacteria and other organisms due to excretion of grazers and

- breakage during handling by grazers into fragments. Processes, independent of grazing, leading to changes in particle size distribution due to

- primary production

- grazing by additional components and

- bacterial growth on detrital particles and the formation of detrital flocs.

     

Effet des androgènes sur l’activité sportive

Androgenic hormones seem to be of beneficial effects on sports performance:

- they increase motivation, will, aggressiveness, resistance to the stress and to the fatigue, leading to an increase of the training quantity,

- they increase bone mineralization and probably mechanical resistance,

- they stimulate the bone marrow and so, with the erythropoietin, the erythropoiesis,

- they increase the tendancy to hyperglycemia, but with a decrease of the tolerance to the glucose,

- they stimulate the fatty acids mobilization from the adipose tissue, for their utilization in the muscle during the exercise,

- they participate, for the trained sportmen, to a better gestion of the muscle glycogen storage: their utilization during exercise is decreased,

- they increase the lean body mass, with an increase of the protein synthesis and a decrease of the protein catabolism, leading also to an increase of the muscle force under training. There is no beneficial effect upon the tendons,

- they have an immunomodulation action.

     

The use of a continuous assay system to show the stimulation of phosphoenolpyruvate production in intact mitochondria by valinomycin and by Mn2+

1. A method for the direct recording of the PEP efflux from isolated mitochondria is described.
2. This method has been used to show the stimulation of PEP efflux by externally added Mn⁺⁺ ions.
3. Valinomycin, uncoupler and oleate were also shown to stimulate PEP efflux.
4. Valinomycin caused an increase in the internal concentration of both PEP and citrate.
5. The results indicate that the major pathway of PEP synthesis in isolated mitochondria is via PEP carboxykinase and the results do not call for an unknown pathway of metabolism.
6. Two interactions between PEP and citrate are described; competition for the mitochondrial interior and the stimulation of PEP production by citrate.

     

Charakterisierung eines phagenähnlichen Partikels aus Zellen von Nitrobacter

1. Polyhedral particles were isolated from cells of Nitrobacter winogradskyi and of Nitrobacter strains K₁, K₄ and α₁. Their physical and biological properties are characterized.
2. The investigated strains contain polyhedral particles, 1000–1200 Å in size. With increasing age of the culture more particles are found in cells of Nitrobacter. Simultaneously the number of colony producing nitritoxidants decreases.
3. In strain α₁ the loss of the capability to form colonies is connected with partial lysis of the cell and release of particles.
4. A homogeneous fraction of particles was obtained by zone density gradient centrifugation in Tris-Mg-SH-buffer.
5. The polyhedral particles have a sedimentation coefficient of s _w,20 ⁰ =825S and a CsCl-buoyant density of ?²⁵ g/cm³.
6. Based on the determined properties the particles are classified as phage-like Nitrobacter particles Nb₁.

     

Growth of a floating aquatic weed,Salvinia under standard conditions

1. Growth of the floating aquatic weed, Salvinia, in sterile culture was exponential for at least 2 weeks under standardized conditions.
2. Increase in light intensity or in CO₂ resulted in increases in growth rate, but did not extend the exponential period of growth.
3. This aquatic plant, like many others, discriminates against calcium relative to strontium.
4. In culture Salvinia exhibited luxury consumption of N and P.
5. Because of high C/N ratios, Salvinia may not be a favorable source of animal food, but might be useful in nutrient removal schemes.
6. In sterile culture, S. molesta produced fewer leaves than S. minima, but maintained a significant increase in leaf area and dry weight. This may be correlated with the ability of the first species to rapidly spread over tropical waterways.

     

Microbial assimilation of hydrocarbons

1. The fine-structure analysis of the hydrocarbon oxidizing microorganism, Acinetobacter sp., demonstrated a cytoplasmic modification resulting from growth on paraffinic and olefinic hydrocarbons.
2. Intracytoplasmic hydrocarbon inclusions were documented by electron microscopy with chemical identifications obtained by gas chromatography and X-ray diffraction.
3. These results demonstrate the ability of a micro-organism to accumulate hydrocarbon substrates intracellularly which, in turn, indicates transport across the cell membrane.

     

Rigorous and extended application of information theory to the afferent visual system of the cat

1. Intracellular recording were obtained from P-cells of the LGN of the cat. The impulse trains of a single presynaptic retinal ganglion cell and the postsynaptic P-cell were separated by band-pass-filtering and subsequent amplitude discrimination.
2. The rates of information and transinformation for the visual channel from the eye to a ganglion cell and to the connected P-cell were calculated. Input signals to the channel were trains of light flashes of different rate, luminance and spatial distribution.
3. Transinformation was calculated without restrictive assumptions for the code.
4. The transient behaviour of the system in response to a flash was fully considered for information calculations. Additionally, it was ensured that the state of the (adaptive) channel was considered correctly.
5. Information theory was applied in an extended way. The time courses of information transfer were calculated for various flash stimuli and compared with each other.

     

The effects of captivity on the electric organ discharge and plasma hormone levels in Gnathonemus petersii (Mormyriformes)

1. Experiment 1 employed a repeated measures design to examine the effects of captivity on sex differences in the electric organ discharge (EOD) of Gnathonemus petersii, newly imported from Africa, and maintained individually or in groups.
2. On the day of import, males exhibited longer durations of phases 2 and 3 of the EOD and lower peak power spectral frequencies (PPSFs) than females.
3. After 14 days in captivity in the laboratory, the sex differences were eliminated. After 37 days of captivity, all sex differences were still abolished, or even reversed depending on housing conditions. Males exhibited the most dramatic changes in EODs and females appeared to have higher testosterone (T) levels than males.
4. Experiment 2 was designed to investigate the effects of captivity on both behavior and endocrine status in 58 newly imported males. In this independent group design, EOD data and blood were collected from subjects over 15 days.
5. Decreases in phase 3 of the EOD and increases in PPSFs progressed over the 15 day experimental period, becoming statistically significant by days 10 and 15, respectively. Regardless of housing conditions, both T and 11-keto T dramatically decreased to near non-detectable levels by Day 5 in the laboratory.
6. Captivity causes rapid and profound changes in the endocrine system which result in dramatic changes in steroid-sensitive EODs. These findings directly link captivity, hormones, and behavior, and show why feral animals brought into captivity usually do not exhibit sexual behavior.

     

Improvements of the membrane filter method for DNA:rRNA hybridization

We describe and recommend the following improvements of DNA:rRNA membrane filter hybridization methods. One of our aims was to avoid DNA release from filter discs during hybridization.

1. Our hybridization conditions are 2 SSC in aq. dest., with 20% formamide, 50 C, overnight for 16 hr.
2. Duplexing is over in 8–10 hr.
3. Formamide has to be very pure (O.D.≤0.2/cm light path at 270 nm).
4. RNAase treatment: 250 μg/5 ml 2 SSC/filter at 37 C for 1 hr.
5. Our conditions for stepwise thermal denaturation are: 5°C steps from 50C to 90C in 1.5 SSC in 20% formamide.
6. Single-stranded DNA, fixed on membrane filters, and stored in vacuo at 4C, can be used reliably for hybridization for up to 20 months.
7. Concentrated DNA in 0.1 SSC, quick-frozen at ?50 C and stored at ?90 C for up to 2 years can be used for hybridization without much change.
8. A CsCl gradient purification step yields much purer DNA, but increases the release of DNA from filters by about 20%. Filters with 20% more DNA is a compensation.
9. rRNA can be stored for 20 months in SSC or 2 SSC at ?12C without changing the hybridization results.