Solubility characteristics of Micrococcus lysodeikticus membrane components in detergents and chaotropic salts analyzed by immunoelectrophoresis

In order to evaluate the effectiveness and selectivity of various reagents in the solubilization of bacterial membranes, membranes of Micrococcus lysodeikticus were treated with detergents and chaotropic agents. The composition of the extracts so obtained was analyzed by rocket and two-dimensional immunoelectrophoretic techniques. Recovery of succinate-, malate-, and reduced nicotinamide adenine dinucleotide- (NADH) dehydrogenases, ATPase, succinylated lipomannan and cytochromes in the extracts was measured. Treatment with a variety of non-denaturing detergents produced extracts that were generally qualitatively uniform although quantitative differences were observed. The degree of extraction of various components was correlated with the hydrophile-lipophile balance. Several chaotropic agents were also evaluated as reagents for membrane solubilization. These agents were less effective in extraction of bulk protein, but produced extracts enriched in some membrane components.     

Influence of rainfall on sleeping site choice by a group of anubis baboons (Papio anubis)

For diurnal nonhuman primates, shifting among different sleeping sites may provide multiple benefits such as better protection from predators, reduced risk of parasitic infection, and closer proximity to spatially and temporally heterogeneous food and water. This last benefit may be particularly important in sleeping site selection by primates living in savanna‐woodlands where rainfall is more limited and more seasonally pronounced than in rainforests. Here, we examined the influence of rainfall, a factor that affects food and water availability, on the use of sleeping sites by anubis baboons (Papio anubis) over two 13‐month study periods that differed in rainfall patterns. We predicted that during wet periods, when food and water availability should be higher, the study group would limit the number of sleeping sites and would stay at each one for more consecutive nights than during dry periods. Conversely, we predicted that during dry periods the group would increase the number of sleeping sites and stay at each one for fewer consecutive nights as they searched more widely for food and water. We also predicted that the group would more often choose sleeping sites closer to the center of the area used during daytime (between 07:00 and 19:00) during wet months than during dry months. Using Global Positioning System data from collared individuals, we found that our first prediction was not supported on either monthly or yearly timescales, although past monthly rainfall predicted the use of the main sleeping site in the second study period. Our second prediction was supported only on a yearly timescale. This study suggests that baboons’ choice of sleeping sites is fluid over time while being sensitive to local environmental conditions, one of which may be rainfall.     

Extracellular enzyme localization during interspecific fungal interactions

Abstract Confronted colonies of Phlebia radiata, P. rufa, Coriolus versicolor, Stereum hirsutum, Phanerochaete velutina and Hypholoma fasciculare showed spatially and temporally heterogeneous patterns of loccase-α-naphthol and peroxidase activities. These activities were coincident in axenic cultures. but were not always so during interaction. Confrontation between species resulted in induction of phenoloxidase activities, even within coenocytic colony regions of Phlebia species which were normally void of such activities in axenic culture. These events resulted in restriction of C. versicolor growth during interaction with P. rufa.     

Molecular analysis of yellow fever virus 17DD vaccine strain.

The Oswaldo Cruz Foundation produces most of the yellow fever (YF) vaccine prepared worldwide. As part of a broader approach to determine the genetic variability in YF 17D seeds and vaccines and its relevance to viral attenuation the 17DD virus was purified directly from chick embryo homogenates which is the source of virus used for vaccination of millions of people in Brazil and other countries for half a century. Neutralization and hemagglutination tests showed that the purified virus is similar to the original stock. Furthermore, radioimmune precipitation of 35S-methionine-labeled viral proteins using mouse hyperimmune ascitic fluid revealed identical patterns for the purified 17DD virus and the YF 17D-204 strain except for the 17DD E protein which migrated slower on SDS-PAGE. This difference is likely to be due to N-linked glycosylation. Finally, comparison by northern blot hybridization of virion RNAs of purified 17DD with two other strains of YF 17D virus revealed only genome-sized molecules for all three viruses. These observations suggest that the vaccine phenotype is primarily associated with the accumulation of mutations.     

Efficient immortalization and morphological transformation of human fibroblasts by transfection with SV40 DNA linked to a dominant marker

Immortal cell lines are essential for genetic and biochemical studies. Unlike rodent cells, which will form continuously growing cultures either spontaneously or after infection with an oncogenic virus (e.g., Simian Virus 40 (SV40)), human cells fail to form continuous cell lines spontaneously and in only rare cases from cell lines after oncogenic virus infection. We have used a plasmid (pSV3gpt) containing both the SV40 early region encoding T antigen and the bacterial gene xanthine-guanine phosphoribosyl transferase (gpt) to achieve high efficiency morphological transformation and immortalization of primary human skin fibroblasts. Transfection of this plasmid into primary human skin fibroblasts derived from a normal individual, two Cockayne's syndrome patients, and an immuno-deficient patient and selection for the gpt gene resulted in an altered cell morphology and growth properties characteristic of previously described SV40-transformed cells. Transfected cultures subsequently senesced, entered crisis and in each case formed a rapidly growing culture. The high efficiency of immunortalization described here (four out of four cell strains) is in contrast to previously described procedures utilizing focal overgrowth. We suggest that the use of a dominant selectable marker linked to the SV40 early region increases the probability of establishing an immortal human cell line.