Search PubMed⌕ Search

Biomedical subjects

L D Smith

Publications and source records attributed to L D Smith.

At least 181 records · Page 10Linked to original sources
PubMed1965

Protein synthesis in enucleated eggs of Rana pipiens.

Tritiated leucine of high specific activity was injected into enucleated Rana pipiens eggs. After 6 hours, there was significant, incorporation of the label into protein. The amount of incorporation in these eggs was as great as that in fertilized, normally developing eggs.

Animals↗
PubMedDate not supplied

Reversible inhibition of translation by Xenopus oocyte-specific proteins.

A characteristic of growing oocytes of all animal species is the synthesis and accumulation of messenger RNA which is destined to be used primarily by the early embryo. The mechanism(s) which regulates the translation of this maternal mRNA remains unknown. However, the inability of the oocyte to translate all of its putative mRNA has been attributed to at least three limitations: (1) The rate of translation is limited by the availability of components of the translational apparatus other than mRNA, (2) the structural organization of the mRNA prevents translation, and (3) proteins associated with the mRNA prevent translation. Several investigators have suggested that proteins associated with maternal mRNA suppress translation in sea urchin eggs, although others claim that such results may be due to experimental artefacts. Oocyte-specific proteins have been identified in association with non-translating poly(A)+ mRNAs from Xenopus laevis oocytes, and we report here that when these proteins are reconstituted with mRNAs in vitro the translation of the mRNAs in vitro is reversibly repressed. The implication is that these proteins are involved in the regulation of translation of stored maternal mRNAs.

Animals↗
PubMedDate not supplied

Virulence factors of Clostridium perfringens.

Clostridium perfringens produces a variety of virulence factors. The mechanism of action of these factors usually falls into one of three groups. Some of these virulence factors, such as the alpha toxin, which is phospholipase C, and the kappa toxin, which is a collagenase, are enzymes that hydrolyze substances essential to the integrity of membranes or other body structures. Other virulence factors, such as the beta, episolon, and iota toxins, act primarily on the vascular endothelium, causing increased capillary permeability, especially in the brain. Still others, such as the delta and theta toxins, are essentially hemolysins. Theta toxin is similar in action and serologically related to streptolysin O.

Bacterial Toxins↗
PubMedDate not supplied

Clostridium botulinum: characteristics and occurrence.

Clostridium botulinum is not a well-defined species of bacterium. Instead, it is a conglomerate of four culturally distinct groups of organisms that, among them, produce seven serologically distinct toxins, all with similar pharmacological action. The principal habitat of C. botulinum is the soil, although its distribution in the soil is sometimes highly regional. Infant botulism is caused by two types of C. botulinum: type A and the proteolytic strains of type B. Type A strains, to whose toxin humans seem most susceptible, are found most frequently in the soil of the western United States; type B strains are somewhat more universally distributed, with a higher frequency of isolation from the soil of some Appalachian areas. The frequency of occurrence of type A and type B food-borne botulism parallels the distribution of these types in the soil.

Clostridium botulinum↗