A mutant lymphoma cell line with a defectiveThy-1 glycoprotein gene

We characterized a mutant T -cell lymphoma line selected for the inability to express the Thy-1 glycoprotein. This cell line is a member of the D complementation class of Thy-1^– somatic cell mutants, and it lacks detectable cell-surface Thy-1.1 glycoprotein and detectable cytoplasmic Thy-1 mRNA. Southern blot analysis using a number of probes isolated from the clonedThy-1.2 gene demonstrated that, in the mutant, one copy of theThy-1 gene is absent from the genome and the other has undergone rearrangement. This rearrangement results from a deletion of the 5 portion of the gene removing the first two alternate exons and promoters and a portion of the second intron. The deletion breakpoint within the mutantThy-1 gene was localized to within 400 nucleotides by Southern blot analysis. The breakpoint is near two classes of mouse repetitive elements-a mouse B1-family repetitive element and a simple repetitive sequence-suggesting a mechanism of rearrangement leading to the mutation. Southern blot analysis demonstrated that two closely linked molecular markers on chromosome 9 are unaltered, demonstrating that the deletion in this mutant cell line is subchromosomal.     

Species-specific algal responses to zooplankton: experimental and field observations in three nutrient-limited lakes

A series of 4-day manipulations of zooplankton biomass and nutrientavailability was performed in enclosures in three lakes to determinespecies-specific algal responses to herbivory and nutrient enrichment.Algal performance in enclosures was compared to the relationshipsbetween weekly algal growth rates and the zooplankton in situ.When in situ growth rates were significant functions of zooplanktonbiomass, the responses were generally consistent with responsesin the enclosure experiments. The importance of both nutrientsand zooplankton in mediating algal growth was demonstrated bynumerous observations: strong algal community response to enrichment,unimodal or positive responses of certain algal taxa to zooplanktonbiomass, differences in degree of nutrient limitation amongthe algal response types, lack of nutrient limitation of non-grazedalgal taxa and a preponderance of taxa with no net responseto increasing zooplankton biomass. Variation in the zooplanktoncommunity may be the largest source of variability in nutrientsupply rate during summer in stratified lakes, and causes substationalvariability in the algae. Algae responded more strongly to changesin zooplankton composition than to changes in zooplankton biomass.We conclude that, due to the close coupling of phytoplanktonand zooplankton communities in these nutrient-limited lakes,major compositional changes in the zooplankton have greatereffects on the algae than do changes in biomass of grazers alreadypresent. ¹Present address: Division of Environmental Studies, Universityof California, Davis, CA 95616, USA ²Present address: Division of Biological Sciences, Universityof California, Davis, CA 95616, USA     

Intraspecific cross-protection in mice immunized with irradiated Schistosoma mansoni cercariae

Several laboratory-maintained strains of Schistosoma mansoni were tested for their relative immunogenicity or susceptibility to anti-schistosome immunity in irradiated cercaria-immunized mice. A total of 11 strains and substrains were used; 7 were of Puerto Rican origin, 3 from Brazil, and 1 from Egypt. Mice were immunized by percutaneous exposure to 50-krad-irradiated cercariae. Immunity was assessed following challenge with cercariae of the homologous or a heterologous strain. The results showed that the choice of either the challenge or immunizing strains was not critical in the development of significant levels of protection. Extensive degrees of cross-protection developed in all intrastrain combinations tested.     

‘Mental’ in ‘southie’: Individual,family, and community responses to psychosis in South Boston

The deinstitutionalization of psychiatric patients is a deeply cultural as well as political task. It entails the sharing of responsibility for human distress with family and community. Consequently, the locus of social control has also shifted from psychiatric and medical expertise to community and legal institutions. Diagnosis and treatment models must be more compatible with lay explanatory models. This paper explores the various meanings of going mental and being mental in the white, working class, ethnic neighborhood of South Boston. The data are extracted from a study of the impact of deinstitutionalization on a cohort of middle-aged, psychiatric patients discharged from Boston State Hospital in the attempt to return them to community living. Individual, family, and community responses to, and interpretations of, the symptoms of mental distress are discussed. The study indicates that even seriously disturbed individuals are sensitive to cultural meanings and social cues regarding the perception, expression, and content of psychiatric episodes. While madness invariably disenfranchises, it does not necessarily deculturate the individual.     

The relative toxicity of a spore preparation of Bacillus thuringiensis var. israelensis against fourth instar larvae of Aedes aegypti and Toxorhynchites amboinensis: suspension feeding compared with enemas and forced feeding

The toxic effect of a spore preparation of Bacillus thuringiensis var. israelensis Berliner Serotype H-14 (Bti) on 4th instar larvae of Aedes aegypti L. and Toxorhynchites amboinensis (Doleschall) was observed when given either in a suspension feeding test or when injected orally as a forced feeding or via the anus as an enema. The A. aegypti larvae showed the greater sensitivity to Bti both because they greatly concentrate the toxin by filter feeding and they are more sensitive to Bti than are the larvae of T. amboinensis. The latter appeared approximately two-fold less sensitive to Bti than the former after taking into account their greater body weight.

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Résumé La toxicité sur des larves de 4ème stade de A. aegypti et T. amboinensis, d'une préparation de spores de B. thuringiensis var. israelensis Berliner sérotype H-14, a été examinée après: injection orale par alimentation forcée, injection anale comme lavement, — le témoin étant une alimentation à partir d'une suspension de spores.Les larves de A. aegypti ont présenté la plus grande sensibilité au Bti d'une part parce qu'elles concentrent beaucoup la toxine avec leur alimentation par filtration, et parce qu'elles sont plus sensibles sensu stricto au Bti. Même en tenant compte de leur poids plus élevé, T. amboinensis est apparu comme deux fois moins sensible au Bti.

     

Microflora associated with the internal surfaces of rubber and stainless steel milk transfer pipeline

Sterile sections of rubber and stainless steel milk transfer pipeline were inserted sequentially into a milking installation and soiled with fresh raw milk over a period of 5 d. The resultant adherent microbial population was removed and the generic composition of mesophilic and psychotropic types was determined. In all cases Acinetobacter spp. were found to predominate (59.5-75.6%). The generic composition of the raw milk used to soil the milking unit (with inserted pipe section) was determined once during each 5-d soiling period. In general the milk was found to contain a mixed flora in which Gram-positive organisms predominated.     

Relationship between nuclear DNA synthesis and centrosome reproduction in sea urchin eggs

The importance of nuclear DNA synthesis for the doubling, or reproduction, of centrosomes in cells that are not growth-limited, such as sea urchin eggs, has not been clearly defined. Studies of enucleated, fertilized eggs show that nuclear activities are not required at each cell cycle for the normal reproduction of the complete centrosome. However, other studies report that the inhibition of nuclear DNA synthesis in intact eggs by the drug aphidicolin prevents centrosome reproduction and entry into mitosis as seen by nuclear envelope breakdown. To resolve this paradox, we systematically characterized the effect of aphidicolin on cell division in eggs from three species of sea urchins. Eggs were continuously treated with 5 or 10 micrograms/ml aphidicolin starting 5 min after fertilization. This blocked total incorporation of 3H-thymidine into DNA by at least 90%, as previously reported. We found that the sperm aster always doubles prior to first mitosis. Over a period of several hours, the centrosomes reproduce in the normal 2-4-8-16 fashion, with a period that is longer and more variable than normal. In every culture, a variable percentage of the eggs undergoes nuclear envelope breakdown. Once broken down, the nuclear envelope never visibly reforms even though centrosomes continue to double. Fluorescent labeling of DNA revealed that the chromatin does not condense into discrete chromosomes. Whether or not the nuclear envelope breaks down, the chromatin appears as an amorphous mass of fibers stretched between first two and then four asters. Later, the nuclear envelope/chromatin loses its association with some or all centrosomes. Our results were the same for all eggs at both drug concentrations. Thus, nuclear DNA synthesis is not required for centrosome reproduction in sea urchin eggs.     

Genetic mechanisms of tumor-specific loss of 11p DNA sequences in Wilms tumor.

Wilms tumor, a common childhood renal tumor, occurs in both a heritable and a nonheritable form. The heritable form may occasionally be attributed to a chromosome deletion at 11p13, and tumors from patients with normal constitutional chromosomes often show deletion or rearrangement of 11p13. It has been suggested that a germinal or somatic mutation may occur on one chromosome 11 and predispose to Wilms tumor and that a subsequent somatic genetic event on the normal homologue at 11p13 may permit tumor development. To study the frequency and mechanism of such tumor-specific genetic events, we have examined the karyotype and chromosome 11 genotype of normal and tumor tissues from 13 childhood renal tumor patients with different histologic tumor types and associated clinical conditions. Tumors of eight of the 12 Wilms tumor patients, including all viable tumors examined directly, show molecular evidence of loss of 11p DNA sequences by somatic recombination (four cases), chromosome loss (two cases), and recombination (two cases) or chromosome loss and duplication. One malignant rhabdoid tumor in a patient heterozygous for multiple 11p markers did not show any tumor-specific 11p alteration. These findings confirm the critical role of 11p sequences in Wilms tumor development and reveal that mitotic recombination may be the most frequent mechanism by which tumors develop.     

Influence of Nitrogen Fertilizers on Growth, Spore Production and Germination, and Biocontrol Potential of Trichoderma and Gliocladium

The mycelial weight of eight out of nine isolates of Trichoderma spp. and Gliocladium virens increased in media supplemented with 2000 mg/l of nitrogen (N) from the fertilizers NH₄Cl, NaNO₃, and a commercial 20–20–20. In general, the greatest increase in growth (up to 311 %) occurred with 20–20–20. The extent of growth was similar with either NH₄Cl or NaNO₃, but was less than that with 20–20–20. Measured by radial development on agar surfacesgrowth of isolates was either not affected or was constricted by supplemental fertilizers. Production of conidia by six out of eight isolates was stimulated by 20–20–20 but not by NH₄Cl or NaNO₃. Germination of conidia of all isolates, generally was high (> 85 %) on amended and nonamended agar. Chlamydospore formation by three Trichoderma isolates in liquid media was not affected by fertilizers. Antagonism or overgrowth of the pathogen Rhizoctonia solani by Trichoderma isolates in culture was reduced appreciably by NaNO₃, but was not affected by NH₄Cl or 20–20–20. Addition of 20–20–20 to natural soil did not reduce further the survival of R. solani caused by germling preparations of six out of seven Trichoderma isolates. However, reduction in survival of the pathogen caused by a T. hamatum isolate was stimulated further (45 %) by the fertilizer.     

Catalytic competence of human alpha- and gamma-thrombin in the activation of fibrinogen and factor XIII

Steady-state kinetic parameters were compared for the action of alpha- and gamma-thrombin on the physiologically important thrombin substrates fibrinogen and factor XIII at 37 degrees C, pH 7.4, and 0.14 M NaCl. gamma-Thrombin, an alpha-thrombin derivative proteolytically cleaved at R-B73 and K-B154, was observed to catalyze the release of fibrinopeptide A (FPA) from fibrinogen with a specificity constant (kcat/Km) of 5 X 10(3) M-1 s-1. This value was approximately 2400-fold lower than the specificity constant for the corresponding alpha-thrombin-catalyzed reaction. The low specificity constant was attributed to an increase in Km and a decrease in kcat for gamma-thrombin-catalyzed release of FPA from fibrinogen. Conversion of alpha-thrombin to gamma-thrombin also resulted in an approximately 800-fold reduction in the specificity constant for thrombin-catalyzed release of fibrinopeptide B (FPB) from fibrin I, as well as a loss in discriminatory power. Whereas alpha-thrombin preferentially released FPA from intact fibrinogen, gamma-thrombin released FPA and FPB from intact fibrinogen at similar rates. In contrast to the large difference in specificity constants observed for alpha- and gamma-thrombin catalysis with fibrin(ogen) as substrate, the specificity constant (2.6 X 10(4) M-1 s-1) observed for gamma-thrombin-catalyzed release of activation peptide from factor XIII was only 5-fold lower than the corresponding value for the alpha-thrombin-catalyzed reaction. Additionally, the promotion of factor XIII activation by fibrin characteristic of the alpha-thrombin-catalyzed reaction did not occur in the gamma-thrombin-catalyzed reaction.(ABSTRACT TRUNCATED AT 250 WORDS)