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We present a protocol for measuring the absolute number of mRNA molecules from a gene of interest in individual, chemically fixed Escherichia colicells. A set of fluorescently labeled oligonucleotide probes is hybridized to the target mRNA, such that each mRNA molecule is decorated by a known number of fluorescent dyes. Cells are then imaged using fluorescence microscopy. The copy number of the target mRNA is estimated from the total intensity of fluorescent foci in the cell, rather than from counting discrete 'spots' as in other currently available protocols. Image analysis is performed using an automated algorithm. The measured mRNA copy number distribution obtained from many individual cells can be used to extract the parameters of stochastic gene activity, namely the frequency and size of transcription bursts from the gene of interest. The experimental procedure takes 2 d, with another 2–3 d typically required for image and data analysis.

Viral infection begins with the binding of a virus to a specific target on the surface of the host cell, followed by viral genome delivery into the host and a continuation of the infection process. Before binding occurs, the virus must first find its receptor by a process whose details are largely unknown. We applied high-resolution fluorescence microscopy and single-particle tracking to elucidate the target-finding process in bacteriophage λas it infects an Escherichia colicell. By monitoring the motion of individual viruses through the early stages of infection, we identified a unique spatial focusing process that allows a virus to arrive from its initial random landing site to its destination at the cell pole. The search process is governed by the interaction between the virus and the LamB receptors, and by the spatial organization of the receptor network on the cell surface. Our findings allowed us to develop a theoretical model for the target-finding process that reproduces the key features observed in experiment. We discuss the possible implications of our findings for the process of viral receptor-finding in higher systems.

The rapid accumulation of genetic information generated by the Human Genome Project and related research has heightened public awareness of genetics issues. Education in genome science is needed at all levels in our society by specific audiences and the general public so that individuals can make well-informed decisions related to public policy and issues such as genetic testing. Many scientists have found that an effective vehicle for reaching a broad sector of society is through high school biology courses. From an educational perspective, genome science offers many ways to meet emerging science learning goals, which are influencing science teaching nationally. To effectively meet the goals of the science and education communities, genome education needs to include several major components-accurate and current information about genomics, hands-on experience with DNA techniques, education in ethical decision-making, and career counseling and preparation. To be most successful, we have found that genome education programs require the collaborative efforts of science teachers, genome researchers, ethicists, genetic counselors, and business partners. This report is intended as a guide for genome researchers with an interest in participating in pre-college education, providing rationale for their involvement and recommendations for ways they can contribute, and highlighting a few exemplary programs. World Wide Web addresses for all of the programs discussed in this report are given in Table 1. We are developing a database of outreach programs offering genetics education () and request that readers submit an entry describing their programs. We invite researchers to contact us for more information about activities in their local area.

Low-density lipoproteins (LDL) have been shown to cause aggregation of human blood platelets at concentrations above 2 g of protein/l. The secretion of the contents of platelet dense granules was detected, but not that of the lysosomes. LDL gave rise to a mobilization of [3H]arachidonic acid from phospholipids and the appearance of products of the cyclo-oxygenase pathway after only 10 s. LDL-promoted aggregation was inhibited by both aspirin and indomethacin. There was an increase in 3H-labelled diacylglycerols and the phosphorylation of 47 kDa proteins. LDL therefore shares at least some of the mechanisms of stimulus/response coupling with those of other agonists.

Low-density lipoproteins (LDL) are thought to influence directly the sensitivity of platelets, but this may only be the case when the LDL are modified by oxidation. In diabetes, LDL are known to be modified by non-enzymatic glycosylation, especially when the blood glucose concentrations are poorly controlled: platelet activation is also concomitantly increased as is the concentration of plasma lipid peroxides.In this study we found that mild oxidation of LDL in vitro is more potent than strongly oxidised LDL in terms of the activation of platelets. Glycosylation of LDL per se has little effect on the aggregation of isolated platelets.

The properties of human hepatoma cell lines in relation to their ability to aggregate isolated human platelets were investigated because of the possible relevance to tumour metastasis. Mahlavu, HepG2 and SK55 cells were all able to aggregate platelets irreversibly, but required the presence of small amounts of plasma, which could not be replaced by fibrinogen or other common plasma proteins. They also required the presence of Ca2+. The plasma factor was non-dialysable and heat-labile. In the case of Mahlavu cells and SK55 cells the aggregatory activity was released from the cells as a non-dialysable material of high molecular weight. HepG2 cells were required intact and did not release materials which induced platelet aggregation. In all cases the aggregation was inhibited by hirudin. However, the requirements for plasma factors suggested that the material was not thrombin itself.The aggregatory property of all the cells was inhibited by prostacyclin and in the case of Mahlavu and HepG2 cells, to a lesser extent by nitric oxide. Addition of very small numbers of bovine aortic endothelial cells (but not human umbilical cord cells) inhibited the aggregation induced by Mahlavu and HepG2 cells, but not SK55 cells. If the endothelial cells were pre-treated with aspirin, this inhibitory property was abolished, indicating that a cyclo-oxygenase product was the principal agent.

A boy, aged almost 10 years, of good physique, nutrition and general health, was sent home from school on Wednesday, Feb. 6, 1935, with the diagnosis of German measles and the information that a physician was not needed for this disease. He did not seem very sick and his rash was about gone by Friday night.Saturday he was irritable, ate very little and slept much of the day. Sunday he wakened apparently well, had a rising bedtussle with his 5 year old brother, made several trips downstairs and read the "funnies." About 9 o'clock in the morning, while talking with his mother, he fell unconscious to the floor. Arriving soon afterward I found him absolutely unconscious, with pupils widely dilated, equal and without reflex. Superficial reflexes were gone; the patellar was faint, and the Babinski sign was positive. The eardrums were normal in appearance. He was