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In the guinea pig anaphylatoxin produces mast cell damage that is similar to that produced by antigen-antibody reaction but is different from that produced by chemical histamine liberators. This damage is inhibited by iodoacetate, p­chloromercuribenzoate, phenol and cold, but is not inhibited by calcium lack or previous heating of the tissue to 45° C. Mepyramine reduces but does not abolish the contraction of the ileum produced by anaphylatoxin. Previous heating of a sensitized ileum to 45° C., although completely abolishing the anaphylactic response, does not interfere with the contraction induced by anaphylatoxin. Furthermore desensitization to anaphylatoxin does not modify the anaphylactic contraction. The implication of anaphylatoxin with the anaphylactic reaction is discussed. It is concluded: (a) that anaphylatoxin shares with the anaphylactic reaction part of the pathway leading to histamine release; (b) that the mechanism of action of anaphylatoxin is quite different from that of the chemical histamine liberators. [ABSTRACT FROM AUTHOR]

The article focuses on the seasonal heat resistance limits of the plants in Western Australia and their connection with water deficits, cell sap properties as well as the regeneration ability of heat damaged plants. Based on earlier literature on leaf heat resistance limits for arid and semi-arid regions in Western Australia, semi-succulent and woolly, mesophytic species have higher resistance values compared to Acacia. In 1969, researcher W. Schwarz observed that the heat resistance limit of Pinus cembra and Rhododendron ferrugineum is affected by the prevailing temperature, the daylength and the endogenous rhythm.

Artificial tetraploids of the Linum perenne group closely resemble their diploid progenitors in macroscopic characters, but differ markedly in their pollen morphology. The pollen of the diploids invariably has three furrows, that of the natural tetraploids normally has six pores and that of the artificial tetraploids typically has six furrows. The pollen of the artificial tetraploids is particularly variable because of tendencies towards syncolpy and the asymmetrical arrangement of furrows. The artificial autotetraploids tend to have lower pollen fertilities and more meiotic irregularities than the artificial allotetraploids. None of the artificial tetraploids resembled the natural tetraploid L. perenne subsp. anglicum particularly closely, but its origin is discussed in the light of the available evidence. [ABSTRACT FROM AUTHOR]

Effects of a nonionic surface active agent (lauroyl/myristoyl di (z-hydroxyethyl) amide) and one anionic surfactant (sodium (linear) dodecylbenzene sulphonate) on cell ultrastructure were determined using Pizaloenopsis protocorms. There were no observable effects after 5 days exposure to woo ppm of the nonionic. However, the anionic caused severe damage. Drastic changes in morphology, loss of membranes, swelling of thylakoids and appearance of dense osmophilic granules were evident in chloroplasts. Other effects include disintegration of polysomes into monosomes; swelling of mitochondria; dispersion of chromatin in the nucleus; appearance of unidentified vesicles in the cytoplasm and plasmolysis of cells. These ultra- structural changes can be attributed to the possible emulsification of membrane lipids as well as precipitation and dispersion of cellular proteins. [ABSTRACT FROM AUTHOR]

Defects in thyroid hormone production, transport and utilization are classified. Particular attention is given to inherited intrathyroidal defects in hormone synthesis which impair thyroid function and lead to goitre formation and hypothyroidism. Anomalies in biosynthesis may also result from disease or drugs. Reference is made to the derangement of iodine metabolism that results from iodine deficiency and from insufficient TSH. Illustrative clinical problems with regard to transport and utilization are quoted, and it is inferred that they lie in rather neglected areas. Throughout an attempt has been made to show how the clinical problems that are encountered in practice may, by the techniques of investigation available to us, be related to the theoretical list of defects that are included in the classification. [ABSTRACT FROM PUBLISHER]

The article focuses on some of the molecular mechanisms involved in the regulation of cell function and offers a conceptual framework on the categories of all potential molecular control mechanisms. It talks about the regulation of the general levels of cellular flow of information as a way to systematically deal with achieving cell regulation. The four basic levels at which control can be exerted include the transcription of genetic information from DNA to RNA, the translation of information from RNA to protein, direct modification of a protein's activity, and degradation of protein.