Low molecular weight sulphydryl compounds and the expression of a cell division mutant of Chlamydomonas reinhardi

Excess sleep and fever are central nervous system (CNS) facets of the acute phase response; these responses are induced by microbial products, such as muramyl peptides, via their ability to enhance cytokine production. Although peripheral macrophages are known to digest bacteria, thereby releasing muramyl peptides that, in turn, stimulate cytokine production, it was unknown whether CNS phagocytes such as microglia also had this capacity. Primary cultures of microglia were allowed to phagocytize and digest Staphylococcus aureus radiolabeled with a cell wall-specific marker. Radiolabeled low molecular weight substances released into the culture medium were partially purified and tested for the ability to induce excess sleep, fever, and cytokine production. These substances increased non-rapid eye movement sleep, electroencephalographic slow-wave activity, and brain temperature after intracerebroventricular injection into rabbits. They also induced interleukin-1, tumor necrosis factor, and the interleukin-1 receptor antagonist production in human monocytes. Results suggest that microglia perform fundamental macrophage functions and further implicate microglia as resident immunocompetent cells.

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Hypoxanthine: a low molecular weight factor essential for growth of erythrocyticPlasmodium falciparumin a serum-free medium

Parasitology ◽

10.1017/s0031182000066233 ◽

1996 ◽

Vol 113 (1) ◽

pp. 19-23 ◽

Cited By ~ 34

Author(s):

H. Asahi ◽

T. Kanazawa ◽

Y. Kajihara ◽

K. Takahashi ◽

T. Takahashi

Keyword(s):

Molecular Weight ◽

Basal Medium ◽

Parasite Growth ◽

Low Molecular Weight ◽

Weight Factor ◽

Serum Free Medium ◽

Free Medium ◽

Serum Free ◽

Adult Bovine Serum ◽

A Cell

SUMMARYA low molecular weight factor in a basal medium essential for erythrocyticPlasmodium falciparumdevelopment in a serum-free medium using a cell growth-promoting factor derived from adult bovine serum was detected. The factor was hypoxanthine. The optimal hypoxanthine concentration for parasite growth was between 15 and 120 μM. The contribution of hypoxanthine to increased parasite growth was clearly evident in cultures on day 4. Among various low molecular weight supplements tested, adenine, adenosine, AMP, ATP, cyclic AMP, guanine, guanosine, inosine, inosine mono-phosphate, xanthine, NAD, NADH, NADP, NADPH and deoxyguanosine triphosphate showed a similar effect to that of hypoxanthine in the serum-free culture system. On the other hand, the addition of uric acid, FAD, thymidine, uridine, orotic acid, deoxythymidine triphosphate, deoxycytidine triphosphate, deoxyadenosine triphosphate, ribose-1-phosphate, or ethanolamine was not beneficial to the parasite growth. The results presented here will not only be of practical value, but will provide important information about the developmental requirements of the parasite.

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In vivo effects of microinjected alkaline phosphatase and its low molecular weight substrates on the first meiotic cell division in Xenopus laevis oocytes.

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.81.16.5150 ◽

1984 ◽

Vol 81 (16) ◽

pp. 5150-5154 ◽

Cited By ~ 18

Author(s):

J. Hermann ◽

O. Mulner ◽

R. Belle ◽

J. Marot ◽

J. Tso ◽

...

Keyword(s):

Molecular Weight ◽

Alkaline Phosphatase ◽

Cell Division ◽

Xenopus Laevis ◽

Low Molecular Weight ◽

Xenopus Laevis Oocytes ◽

Meiotic Cell ◽

In Vivo Effects

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Inhibition of the Replication of a Hepatitis C Virus-Like RNA Template by Interferon and 3′-Deoxycytidine

Antiviral Chemistry and Chemotherapy ◽

10.1177/095632020201300604 ◽

2002 ◽

Vol 13 (6) ◽

pp. 363-370 ◽

Cited By ~ 5

Author(s):

Robert W King ◽

Marianne Zecher ◽

Matthew W Jefferies

Keyword(s):

Molecular Weight ◽

Hepatitis C Virus ◽

Hepatitis C ◽

Cell Line ◽

Nucleoside Analogue ◽

Luciferase Activity ◽

Low Molecular Weight ◽

A Cell ◽

Good Cell ◽

Accurate Quantification

The development of low molecular weight inhibitors of hepatitis C virus (HCV) replication has been hindered by the lack of a good cell-based system that models the entire HCV replication cycle. To date the only two therapies approved for the treatment of HCV infection are interferon (IFN)-α and the nucleoside analogue, ribavirin. We have created a cell-based system that allows for the accurate quantification of the replication of an HCV-like RNA template by proteins that are encoded for by the HCV genome. The system consists of a cell line that constitutively produces luciferase in response to the production of functional HCV replicative proteins. The 293B4α cell line has been formatted into a semi-high throughput, cell-based screen for inhibitors of HCV replication. When these cells were treated with either IFN-α or -β, luciferase production decreased in a dose-responsive manner. Counterscreening these molecules in another cell line, 293SVLuc, in which luciferase production in not dependent the presence of functional HCV proteins, showed that the inhibition of luciferase in the 293B4α cell line was due to inhibition of the replication of the HCV-like RNA template and not anti-cellular or -luciferase activity. Moreover, when the 293B4α cell line was treated with the ribonucleoside analogue, 3′-deoxycytidine, luciferase decreased in a dose-responsive manner. 3′-deoxyguanosine and 3′-deoxyuridine did not inhibit luciferase production and 3′-deoxyadenosine was too cytotoxic to determine if it had any anti-HCV activity

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Selfish bacteria are active throughout the water column of the ocean

10.1101/2021.07.26.453833 ◽

2021 ◽

Author(s):

Greta Giljan ◽

Sarah Brown ◽

C. Chad Lloyd ◽

Sherif Ghobrial ◽

Rudolf Amann ◽

...

Keyword(s):

Molecular Weight ◽

Organic Matter ◽

Water Column ◽

Extracellular Enzymes ◽

Heterotrophic Bacteria ◽

Low Molecular Weight ◽

Surface Ocean ◽

Bottom Waters ◽

A Cell ◽

Hydrolysis Of

Heterotrophic bacteria use extracellular enzymes to hydrolyze high molecular weight (HMW) organic matter to low molecular weight (LMW) hydrolysis products that can be taken into the cell. These enzymes represent a considerable investment of carbon, nitrogen, and energy, yet the return on this investment is uncertain, since hydrolysis of a HMW substrate outside a cell yields LMW products that can be lost to diffusion and taken up by scavengers that do not produce extracellular enzymes1. However, an additional strategy of HMW organic matter utilization, selfish uptake2, is used for polysaccharide degradation, and has recently been found to be widespread among bacterial communities in surface ocean waters3. During selfish uptake, polysaccharides are bound at the cell surface, initially hydrolyzed, and transported into the periplasmic space without loss of hydrolysis products2, thereby retaining hydrolysate for the selfish bacteria and reducing availability of LMW substrates to scavenging bacteria. Here we show that selfish bacteria are common not only in the sunlit upper ocean, where polysaccharides are freshly produced by phytoplankton, but also deeper in the oceanic water column, including in bottom waters at depths of more than 5,500 meters. Thus, the return on investment, and therefore also the supply of suitable polysaccharides, must be sufficient to maintain these organisms.

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A high-performance oil-free backing pump for electron microscopes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107691 ◽

1978 ◽

Vol 36 (1) ◽

pp. 110-111

Author(s):

G.K.W. Balkau ◽

E. Bez ◽

J.L. Farrant

Keyword(s):

Molecular Weight ◽

Electron Microscope ◽

Hot Spots ◽

High Performance ◽

Carbonaceous Material ◽

Contamination Rate ◽

Low Molecular Weight ◽

Principal Source ◽

Rotary Pumps ◽

Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

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