Distribution of genetic diversity in relation to chromosomal inversions in the malaria mosquito Anopheles gambiae

The epidemiology of malaria in Africa is complicated by the fact that its principal vector, the mosquito Anopheles gambiae, constitutes a complex of six sibling species. Each species is characterized by a unique array of paracentric inversions, as deduced by karyotypic analysis. In addition, most of the species carry a number of polymorphic inversions. In order to develop an understanding of the evolutionary histories of different parts of the genome, we compared the genetic variation of areas inside and outside inversions in two distinct inversion karyotypes of A. gambiae. Thirty-five cDNA clones were mapped on the five arms of the A. gambiae chromosomes with divisional probes. Sixteen of these clones, localized both inside and outside inversions of chromosome 2, were used as probes in order to determine the nucleotide diversity of different parts of the genome in the two inversion karyotypes. We observed that the sequence diversity inside the inversion is more than three-fold lower than in areas outside the inversion and that the degree of divergence increases gradually at loci at increasing distance from the inversion. To interpret the data we present a selectionist and a stochastic model, both of which point to a relatively recent origin of the studied inversion and may suggest differences between the evolutionary history of inversions in Anopheles and Drosophila species.     

Prediction of psychosis. A step towards indicated prevention of schizophrenia

BACKGROUND: The identification of people at high risk of becoming psychotic within the near future creates opportunities for early intervention prior to the onset of psychosis to prevent or minimise later ill-health. The present study combines current knowledge about risk factors for schizophrenia with our knowledge of psychotic prodromes in an attempt to identify a group particularly vulnerable to impending psychosis. We wanted to identify people with high likelihood of transition to psychosis within a follow-up period of 12 months, and to determine the rate of transition to psychosis in this group. METHOD: Various state and trait risk factors for psychosis were used alone and in combination to operationally define a putatively high-risk group. Operationalised criteria for onset of psychosis were established. The individuals were assessed monthly on measures of psychopathology for six months. RESULTS: Eight out of 20 people made the transition to frank psychosis within a six-month follow-up period. Follow-up of this group is still in progress, and the 12 month transition rate might prove to be higher still. CONCLUSIONS: We have demonstrated that it is possible to identify individuals with a high likelihood of onset of psychosis within a brief follow-up period. This lays the foundation for early treatment in an attempt to prevent, delay or minimise the severity of first onset of schizophrenia.     

Evaluation of the antineoplastic activity of guduchi (Tinospora cordifolia) in cultured HeLa cells

The transmissible spongiform encephalopathies (TSEs) (in both humans and animals) have been reviewed with the principal focus on bovine spongiform encephalopathy (BSE), its recent outbreak amongst cattle in the UK ('mad cow disease') and its sequelae. The possible reasons for this outbreak are discussed as well as a number of hypotheses reviewed for TSEs (e.g. prions, organophosphates, etc.) and current measures attendant with food safety and surveillance taken in the European Union. It is generally accepted that the combined weight of all the evidence to date supports the conclusion that the new rare but lethal variant Creutzfeldt-Jacob Disease (vCJD) is the human counterpart of the aetiological agent BSE and that eating meat from the infected animals is probably to blame for 24 deaths (23 in the UK and one in France) to date from vCJD. Considerable evidence from biochemical, immunologic, pathologic and genetic studies strongly suggests that PrpSC is the major component of the transmissible prion particle responsible for the rare fatal brain TSE diseases.     

Kinetics of adhesion molecule expression and spatial organization using targeted sampling fluorometry

Cellular interactions with the vascular wall under flow conditions are controlled, in part, by the density of adhesion molecules on endothelial cells. The spatial arrangement and absolute levels of these molecules over the endothelium are therefore important determinants of cellular localization. Many biochemical and functional studies have characterized the interactions between leukocytes and endothelial monolayers, but no reliable method has been reported for quantifying the spatial expression of adhesion molecules on intact endothelial cell monolayers. We report the development of targeted sampling fluorometry (TSF), which uses standard immunostaining, fluorescence microscopy and digital image analysis techniques to analyze cell surface molecule expression on a cell-by-cell basis. This technique is performed on an intact monolayer and results in cellular intensity distributions that reflect spatial heterogeneity in adhesion molecule expression. We demonstrate the use of targeted sampling fluorometry in a study of the kinetics of tumor necrosis factor alpha-induced activation of human umbilical vein endothelial cell monolayers and show that the spatial patterns of adhesion molecule expression correlate with the locations of bound lymphocytes.     

Transformation-induced alterations in the regulation of tyrosine aminotransferase expression in fetal rat hepatocytes: changes in hormone inducibility and the DNase-hypersensitive site

Regulation of expression of tyrosine aminotransferase (TAT) is examined in two cell lines (FRL) obtained by chemical transformation of cultured fetal hepatocytes derived from 19-day rat fetuses (FL19). Steroid induction of TAT is unaffected by transformation, while the response to cyclic AMP is attenuated. Consequently a synergistic response elicited by the simultaneous exposure of normal fetal hepatocytes to the inducers is almost abolished in FRL cells. FL19 and FRL are similar with respect to the negative effect of insulin on steroid induction, which is a response restricted to prenatal liver. Detailed examination of chromatin reveals that the attenuated effect of cyclic AMP is consistent with the lack of the DNase I-hypersensitive site located at about the cyclic AMP response element of the TAT promoter. From the studies, we conclude that transformation results in the modification of some aspects of TAT regulation, while others have been retained, and reflects the fetal pattern which is observed in normal embryonic hepatocytes.     

Effect of a high-beef diet on the fecal bacterial flora of humans

Ten human volunteers completed a 4-month diet series consisting of 1 month each of a control diet, a meatless diet, a high-beef diet, and the same control diet. Fat and fiber contents were essentially the same in all four diets, but protein content was doubled during the high-beef diet. During the 4th week on each diet, three stool specimens collected from each volunteer were analyzed for chemical composition and content of facultative, aerobic, and anaerobic bacteria. The bacteriological data are presented in this paper. High beef protein consumption had little effect on the composition of the intestinal flora. There were no significant differences in total counts of facultative and aerobic or anaerobic organisms in the feces when volunteers were on meatless or high-beef diets. At the species level, when counts during the two control diets were comparable, in only three instances did the change from the meatless to a high-beef diet significantly influence the bacterial numbers. The ratio of mean counts of anaerobic to facultative and aerobic organisms was approximately 15:1 during the meatless diet and 34:1 during the high-meat diet. The data indicate that animal protein consumption has little effect on the fecal bacterial profile in humans.     

Partial replacement of chicken semen by turkey semen in artificial insemination of chickens

Chicken semen undiluted, diluted with a diluent containing fructose and/or mixed with turkey semen was used to inseminate Leghorn hens. In two of three experiments there was an improvement in fertility from insemination by mixed semen as compared to semen diluted to the same extent with the diluent.