The genetic structure of a tribal population,the Yanomama Indians. XII. Biodemographic studies

The Yanomama Indians of Southern Vanezuela and Northern Brazil are one of the largest, relatively unacculturated tribes of the tropical rain forest. Over a period of eight years data have been collected from a considerable portion of their territory on estimated age, sex ratio, fertility rates (as determined by physical examination and urine tests), and infant death rates. Although it has been impossible to collect direct data on infanticide, this subject can be approached indirectly through distortions of the sex ratio and anecdotal information. Some historical data are also available as a basis for estimating tribal expansion in the past 100 years. With this material it has been possible to construct Life Tables for the Yanomama, and to explore the results of various perturbations of the input parameters. Data are also presented on patterns of mating and reproduction: number of spouses, mean and variance in number of surviving children, frequency of “extra-marital conceptions” based on the results of extensive blood group typings, and consanguinity rates as determined by observation and computer simulation. Although we do not present the Yanomama as typical, these data are seen as providing a basis for more realistic population models than have existed in the past. In addition, the data provide a basis for relatively precise estimates of such demographic measures as Fisher's Reproductive Value, Crow's Index of Total Selection, and Weiss' Index of Growth Regulation.     

Heterogeneity and several clinico-genetic correlations in epilepsy under inbred conditions]

The types of inheritance and clinico-genetical correlatins of epilepsy in 291 probands in conditions of inbreeding were studied. The data obtained confirmed the multifactorial (gene-polygene+medium) inheritance of epileptic and convulsive predispositions and contradicted the hypothesis of primarily recessive inheritance of epilepsy. Together with family forms of the disease, which were communicated mainly according to an uncertained and dominant type (rarely recessive type), there were existed forms of eipilepsy with incomplete genetical hereditary predisposition (which were observed in relatives of 2-3 generations only by epileptic features) and phenotypical forms concentrated in sporadic groups. There were found the dependences onthe rate of occurrence of secondary epilepsy (with or without epileptoidness), epileptoid psychopathy and children convulsions in relatives, on the type of inheritance, the age of manifestations, the form, polymorphism of the attacks, the severity of the developement of epilepsy, the expressiveness of epileptoidness in probands and high severity of the disease with distinct epileptoidness inbreeding families. The hereditary heterogeneity of epilepsy, associated, perhaps, with pleiotropy of epileptic (with or without epileptoidness) genes, was assumed. The found clinico-genetical correlaltions mightbe taken into account in medico-genetical prognosis of families burdened by epilspsy in analogous populational-demographic conditions.     

Experimental research on mechanical stresses in the neuroepithelial layers of the brain

The embryonic brain was dissected in urodele amphibians at the early postneurulation stages. Tangential mechanical tensions were shown to exist in the embryonic brain. The reaction of neuroepithelial cells characterizing the topology of tensions was found by the use of dissections in two interperpendicular directions. The cells were oriented along the acting force in the case of unidirectional tension. In the case of two interbalanced tensions the cells were inclined along the lines of force of greater tension. Three types of tangential tensions were revealed which differ in force, direction, range of action and life time. The life times of tangential tensions were shown to depend on their force and range of action. The strongest tensions were short-lived and, besides, limited in space. Weak tensions were long-lived and spread all over the brain. In all cases of dissections the cells inducing tangential tensions reacted in the same way: by elongation of cell bodies along the normals to the brain layer. It is suggested that the tendency of cell elongation can cause the tangential tension of the layer. It was found that the partial removal of tensions enhances the curvatures of brain layers. The cells reacted to the tension removal in accordance with their position in the layer. If the cells are located in the grooves, they are shortened. If the cells are outside the grooves, they are elongated. It was found that after the tension was removed the nuclei migrated along the cell bodies. The migration of the nuclei depends on the direction of the layer flexure. The nuclei always migrated to the external surface of evagination or to the internal surface of flexure. It is suggested that the tangential tensions stabilize the changes in the brain shape.     

Use of transformation for studying the nature of formation of stable bacterial L forms]

The authors obtained a stable variant of the L-forms of Bacillus subtilis capable of exponential growth of the minimal and synthetic medium. An electron-microscopic study of different stages of the L-form formation was carried out by the method of ultra-thin sections. A possibility was shown of the transfer of the L-form formation sign by the method of transformation. DNA isolation from the L-forms by soft lysis considerably facilitated and simplified the genetic analysis of the L-form formation by the transformation method.     

Fragmentation of mitochondrial H+-ATPase hydrophobic complex]

The subunits with molecular weights of 30 000, 10 000 and 20 000 + 19 000 have been obtained by fractionation of the hydrophobic part of the oligomycin-sensitive ATPase complex on Sephadex G-200 and Sephadex G-150 in the presence of sodium dodecyl sulfate.     

Comparative mycobactericidal efficacy of chemical disinfectants in suspension and carrier tests

The efficacy of nine disinfectants on Mycobacterium smegmatis was tested in the presence of sputum, using quantitative suspension and carrier tests. Glutaraldehyde, povidone iodine, and chlorhexidine gluconate produced at least a 6-log10 reduction in CFU in all tests. Four disinfectants (sodium dichloroisocyanurate, phenol, ethanol, and sodium hypochlorite) were not as effective in the carrier tests as in the suspension tests; this difference ranged from a 1- to a 5-log10 reduction in CFU. The efficacy of ethanol and sodium hypochlorite was further reduced (3- and 1-log10 reductions in CFU, respectively) in the presence of sputum. The quaternary ammonium compound and iodophor were ineffective in all tests. The findings of this study demonstrate the need for a quantitative carrier test such as the one presented here.