SCM2, a tryptophan permease in Saccharomyces cerevisiae, is important for cell growth

SCM2, a novel gene encoding a yeast tryptophan permease, was cloned as a high-copy-number suppressor of cse2-1. The cse2-1 mutation causes cold sensitivity, temperature sensitivity and chromosome missegregation. However, only the cold-sensitive phenotype of cse2-1 cells is suppressed by SCM2 at high copy. SCM2 is located on the left arm of yeast chromosome XV, adjacent to SUP3 and encodes a 65 kDa protein that is highly homologous to known amino acid permeases. Four out of five disrupted scm2 alleles (scm2 delta 1-delta 4) cause slow growth, whereas one disrupted allele (scm2 delta 5) is lethal. Cells with both the scm2 delta 1 and trp1-delta 101 mutations exhibit a synthetic cold-sensitive phenotype and grow much more slowly at the permissive temperature than cells with a single scm2 delta 1 or trp1-delta 101 mutation. A region of the predicted SCM2 protein is identical to the partial sequence recently reported for the yeast tryptophan permease TAP2, indicating that SCM2 and TAP2 probably encode the same protein.

Safety and immunogenicity of live attenuated hepatitis A virus vaccine (H2 strain) in humans

A study was made in Neijiang City, Sichuan Province to observe the safety and immunogenicity of a live attenuated hepatitis A virus (HAV) vaccine (H2 strain). 3,031 children, aged 6 to 9 years, were injected subcutaneously with 10(6.0) TCID50, 10(5.5) TCID50, and 10(5.0) TCID50 of HAV vaccine; the seroconversion rate and antibody GMT were 97.52%-90.68%, GMT = 1:5.19 +/- 1.90-1:3.36 +/- 1.94; 84.75%-76.27%, GMT = 1:4.29 +/- 1.96-1:2.0 +/- 2.67; 53.23%-51.61%, GMT = 1:2.57 +/- 1.89-1:1.68 +/- 1.41 respectively after 4 weeks to 12 months of inoculation. Forty-eight children in the control group were anti-HAV negative at 4, 8, and 12 weeks; 21 children in the oral group were not antibody positive 4 and 8 weeks after oral administration of the vaccine. The stool specimens of 3 of the 14 vaccinated children were HAA positive. The results suggest that the live attenuated HAV vaccine (H2 strain) is of good immunogenicity and safety.

CSE1 and CSE2, two new genes required for accurate mitotic chromosome segregation in Saccharomyces cerevisiae

By monitoring the mitotic transmission of a marked chromosome bearing a defective centromere, we have identified conditional alleles of two genes involved in chromosome segregation (cse). Mutations in CSE1 and CSE2 have a greater effect on the segregation of chromosomes carrying mutant centromeres than on the segregation of chromosomes with wild-type centromeres. In addition, the cse mutations cause predominantly nondisjunction rather than loss events but do not cause a detectable increase in mitotic recombination. At the restrictive temperature, cse1 and cse2 mutants accumulate large-budded cells, with a significant fraction exhibiting aberrant binucleate morphologies. We cloned the CSE1 and CSE2 genes by complementation of the cold-sensitive phenotypes. Physical and genetic mapping data indicate that CSE1 is linked to HAP2 on the left arm of chromosome VII and CSE2 is adjacent to PRP2 on chromosome XIV. CSE1 is essential and encodes a novel 109-kDa protein. CSE2 encodes a 17-kDa protein with a putative basic-region leucine zipper motif. Disruption of CSE2 causes chromosome missegregation, conditional lethality, and slow growth at the permissive temperature.

Serum lipids and their correlates in Chinese urban and rural populations of Beijing and Guangzhou. PRC-USA Cardiovascular and Cardiopulmonary Epidemiology Research Group

In 1983 and 1984, surveys were conducted in four Chinese population samples, urban and rural for both Beijing and Guangzhou, as part of PRC-USA collaborative research in cardiovascular and cardiopulmonary epidemiology. Serum total cholesterol (TC), HDL-cholesterol (HDL-C), and triglycerides (TG) were measured in 4280 men and 4695 women aged 35-54 years, in laboratories standardized by the US Centers for Disease Control. Age-adjusted mean serum TC was higher in urban than rural samples and generally higher in Beijing than Guangzhou, ranging from 155 mg/dL for Guangzhou rural women to 187 mg/dl for Guangzhou urban women. Group mean values of HDL-C varied from 48 to 59 mg/dl, higher in Beijing than Guangzhou, and higher in women than men. TC/HDL-C ratio ranged from 3.05 to 3.82. Serum TG values were higher for Beijing than Guangzhou; the lowest group mean values of 78 mg/dl and 75 mg/dl were in rural Guangzhou men and women. Mean body mass index (BMI) was uniformly low, ranging from 20 kg/m2 for rural Guangzhou to 24 kg/m2 for urban Beijing. Multiple regression analyses showed that BMI was positively and independently related to serum TC, LDL-C, TG, and TC/HDL-C, and inversely related to HDL-C. Smoking was positively related in both sexes to TG and TC/HDL-C, and inversely related to HDL-C. Smoking was also positively related to TC and LDL-C in men. In men, alcohol was positively related to TC and HDL-C, and was inversely related to TG and TC/HDL-C. Heavy manual work was inversely related to TC, LDL-C, and TC/HDL-C in men, but not related to lipids in women. Thus, for these Chinese population samples, despite their lower serum TC and BMI, the correlates of serum lipids are similar to those in western populations. These variables accounted for only part of the observed urban-rural and north-south differences in serum lipids among these Chinese population samples. The significance of the relatively low serum TC and TG and high HDL-C in relation to low cardiovascular disease in Chinese populations is the object of further investigation in follow-up studies.

[Preparation of antigen and antibody against aflatoxin B1]

Carboxymethyloxime of aflatoxin B1 (AFB1) was synthesized by refluxing AF B1 with carboxymethoxylamine hemihydrochloride for 4 hours in the presence of pyridine. AF B1-BSA (antigen) was made successfully by coupling AF B1-oxime with bovine serum albumin (BSA) in the presence of a water soluble carbodiimide. The rabbits were immunized with the artificial immunogen which had been purified by dialysis. The titers of antisera were determined by indirect enzyme-linked immunosorbent assay (ELISA) which was developed by ourselves. The highest titer was 1:100,000.

[Study on determination of ammonia-nitrogen in water by ammonia gas sensor electrode]

A method for the determination of NH3-N content in water by ammonia gas sensor electrode was studied systematically. Good results were obtained by adding acid to water samples until pH less than 2 for storage and adding EDTA to prevent metal ions from interference. Recoveries varied in the range of 90-104%, and the coefficients of variation less than or equal to 3.4%. The measurement range was 10(-1)-10(-4)micrograms/ml, and the detection limit 0.13 micrograms/ml. The reliability of the method was confirmed by comparison with Nesslerization (P greater than 0.5). This method is simple, rapid, accurate and can directly be applied to the determination of the content of ammonia-nitrogen in colored and turbid water samples.

[Studies of the determination of selenium by hydride generation atomic absorption spectrometry]

Potassium ferricyanide has a masking effect of Cu2+, Ni2+ and other interferential ions in the determination of selenium by hydride generation atomic absorption spectrometry. Interference was not observed in the determination of 5ng/ml of Se(IV) in the presence of 10micrograms/ml of Cu2+ under recommended conditions. The stability of analyte and potassium borohydride solutions in storage was also studied.

[Study on the fluorimetric determination of aluminum with H2QS and CTMAB in water]

A study on the fluorimetric reaction of Al-H2QS-CTMAB and conditions of the determination of aluminium in water by model 930 fluorimeter is reported. A good linear relationship between the strength of fluorescence and aluminum concentrations, ranging from 0 to 1.5 micrograms/10ml, is observed. Interferences from other constituents in water can be eliminated by the masking effect of 1, 10-phenanthroline and hydroxylamine hydrochloride and by using standard addition method. The coefficient of variation and recovery vary from 2.9% to 8.9% and from 87% to 105%, respectively. The detection limit is 3 x 10(-2) micrograms/ml. This method is rapid, sensitive, accurate and suitable for the determination of contents of aluminum in drinking and natural waters.