Intermittent illumination increases biophotolytic hydrogen yield by Anabaena cylindrica.

Intermittent illumination increased H2 and C2H4 yields per unit of light from growing cells and from nitrogren-starved cells by 1.7- and 1.35-fold, respectively, as compared with continuous illumination.     

Population genetics of coagulant factor IX: frequencies of two DNA polymorphisms in five ethnic groups.

Two frequently used restriction-enzyme polymorphisms (RFLPs) of coagulant F.IX, TaqI and XmnI, have been examined in five ethnic groups: white Americans, black Americans, East Indians, Chinese, and Malays. There is a distinct "cline" in the frequencies of both polymorphisms, from white Americans to Malays. The rarer type 2 alleles of both polymorphisms, in which middle recognition sites are present--and which in our sample reach their highest frequencies in white Americans--are marginally higher in four groups of Europeans previously reported by others. The frequencies of the rarer alleles are significantly higher in Europeans than in black Americans and East Indians, and these alleles are essentially absent in Chinese and Malays. The frequency of heterozygosity diminishes in the same order, being zero in Malays for both polymorphisms. The polymorphisms are in strong linkage disequilibrium, and in all groups the type 1 allele for TaqI is disproportionately accompanied by the type 1 allele for XmnI. The paucity of type 2 alleles and the low rate of heterozygosity in four non-European groups suggest that the polymorphisms will be of little diagnostic value south of Gibraltar and east of Suez. This prediction is confirmed by the observed haplotype frequencies in the black American and the Oriental groups.     

HIV testing: changing trends at a clinic for sexually transmitted diseases in London.

Trends in human immunodeficiency virus (HIV) counselling and antibody testing at a London clinic for sexually transmitted diseases showed substantial changes over a 12 month period. From around 100 a month in the summer of 1986 the numbers of people attending rose substantially to 276 in October 1986 and 475 in November at the time of the campaign in the popular press. They rose further still, to 700, at the time of AIDS (acquired immune deficiency syndrome) week in March 1987. In April they fell to the levels seen six months previously. Apart from this increase in overall numbers the proportions of women and heterosexual men who were seen increased.     

Continuous-Culture Responses of Candida shehatae to Shifts in Temperature and Aeration: Implications for Ethanol Inhibition

Temperature and aeration shifts were used to perturb steady-state continuous cultures to determine the effects of ethanol on xylose metabolism by Candida shehatae. The accumulation of ethanol exerted a delayed inhibitory effect on the specific rate of substrate utilization. A second effect was also observed in which the specific rate of xylitol production increased at the expense of the specific rate of ethanol production. Both effects were enhanced at higher temperature. Inhibitory effects also occurred in glucose metabolism.     

Structure of retinular cells in a Drosophila melanogaster visual mutant,rdgA, at early stages of degeneration

Summary A Drosophila visual mutant rdgA has photoreceptive cells which degenerate gradually after eclosion. Fine structure of the retinular cells of rdgA ^KS60 and rdgA ^K014 was studied during early stages of degeneration to determine the initial morphological defects. The retinular cells of these two alleles showed the following structural abnormality within 1 day after eclosion: (1) rhabdomeres were small and irregular in shape; (2) cisternae of the rough endoplasmic reticulum were more numerous than those in normal retinular cells; (3) submicrovillar cisternae were absent; and (4) lysosomes were fewer than normal. Three-dimensional reconstruction of serial sections of the ommatidia showed that the degeneration of mutant rhabdomeres proceeds more rapidly in regions remote from the nuclei. These results suggest that the process of turnover of rhabdomeric microvilli is abnormal in rdgA. We also confirmed an increase of lysosomes and destruction of cellular organelles, as reported by previous investigators at more advanced stages of degeneration.