A chronic implant for recording of cochlear potentials in primates

A new technique for the continuous recording of peripheral bioelectrical activity in the auditory system of primates is described. Because of basic differences in the anatomy of the temporal bone, the approach to the round window of the cochlea is more difficult in most primates than in lower animals. A relatively simple surgical approach, which made possible the placement of an electrode into the perilymph of the inner ear via the well-demarcated horizontal semicircular canal was therefore developed and is described in detail. The bared tip of a Teflon-coated wire was cemented into the canal opening with carboxylate cement, and the wire attached to a permanent electrical connector on the skull. Cochlear microphonic and action potentials of 50 to 100 μV amplitude were thus recorded on a continuing basis at the same time that behavioral studies of primate auditory acuity were conducted.     

Antitumour activities of levans produced by Zymomonas mobilis strains

Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice. Levans from two strains (ZAP and CP4) had the highest effects. NMR analysis showed that the polymers were composed only of fructose units. The results suggested that the antineoplasic effect is associated to the polysaccharide molecular weight and that a particular molecular weight range may be responsible for this effect.     

Inequalities in women's health: looking at mortality differentials using an alternative approach

Data obtained from follow up of the 1971 census sample in the Office of Population Censuses and Surveys longitudinal study of England and Wales were used to look at women''s mortality differentials at ages 15-59. Women were grouped by combining information on marital state, own occupation, husband''s occupation (if married), economic activity, and indicators of household wealth (housing tenure and access to a car). Large groups were found with considerable differences in mortality. High mortality was associated with working in manual occupations and living in rented housing with no car in the household. In contrast, low mortality was associated with non-manual occupations and living in owner occupied housing with a car. Among married housewives and single women these extreme groups contributed 44% of expected deaths, the disadvantaged group experiencing death rates two and a half times that of the advantaged group. Smaller differences were found among married women with an occupational class.These findings are further evidence of the “health divide” in England and Wales and show that accurately to reflect the relation between a woman''s life circumstances and mortality it is necessary to utilise other measures than those based solely on occupation.     

Characterization of the major duck hepatitis B virus core particle protein.

The amino acid composition of the major duck hepatitis B virus (DHBV) core particle proteins was determined. The results of this analysis indicated that cores are composed of a single major protein that initiates translation from the second available AUG in the DHBV core gene. Proteins isolated from core particles purified from the cytoplasm of DHBV-infected duck hepatocytes exhibited heterogeneity in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, independent of the stage of viral DNA maturation. Incubation of native cores with alkaline phosphatase removed this heterogeneity, indicating that phosphorylation of external amino acids was responsible. Core protein isolated from mature DHBV purified from serum of infected animals did not display heterogeneity, suggesting a possible role for dephosphorylation in virus maturation.     

Variation in the ribosomal internal transcribed spacers (ITS1 and ITS2) among eight taxa of the Mimulus guttatus species complex

The internal transcribed spacer region (ITS1 and ITS2) of the 18S-25S nuclear ribosomal DNA sequence and the intervening 5.8S region were sequenced from three individuals in each of eight taxa of the Mimulus guttatus species complex. Three discrete variants, or "types," of ITS sequences were found, among which 30%-40% of sites differed, compared with 1%-2% within types. Dot plots indicate that these types were not related by conspicuous rearrangements or inversions. More than one ITS type was often found in the same taxon, and two of three ITS types span species boundaries, indicating their presence prior to speciation. These ITS sequences showed essentially no positional homology with the nearest sequenced relative, tomato. In contrast, the 5.8S region was relatively unvaried, with 8 of 162 sites varied in the sample among all eight taxa. The phylogeny inferred by the most common ITS sequence type, rooted by the two other ITS types, agreed with isozymes in showing the distinctness of M. nudatus, M. laciniatus, and M. tilingii from the other five taxa.      

Variation in heat shock proteins within tropical and desert species of poeciliid fishes

The 70-kilodalton heat shock protein (hsp70) family of molecular chaperones, which contains both stress-inducible and normally abundant constitutive members, is highly conserved across distantly related taxa. Analysis of this protein family in individuals from an outbred population of tropical topminnows, Poeciliopsis gracilis, showed that while constitutive hsp70 family members showed no variation in protein isoforms, inducibly synthesized hsp70 was polymorphic. Several species of Poeciliopsis adapted to desert environments exhibited lower levels of inducible hsp70 polymorphism than the tropical species, but constitutive forms were identical to those in P. gracilis, as they were in the confamilial species Gambusia affinis. These differences suggest that inducible and constitutive members of this family are under different evolutionary constraints and may indicate differences in their function within the cell. Also, northern desert species of Poeciliopsis synthesize a subset of the inducible hsp70 isoforms seen in tropical species. This distribution supports the theory that ancestral tropical fish migrated northward and colonized desert streams; the subsequent decrease in variation of inducible hsp70 may have been due to genetic drift or a consequence of adaptation to the desert environment. Higher levels of variability were found when the 30- kilodalton heat shock protein (hsp30) family was analyzed within different strains of two desert species of Poeciliopsis and also in wild-caught individuals of Gambusia affinis. In both cases the distribution of hsp30 isoform diversity was similar to that seen previously with allozyme polymorphisms.      

Sensitivity to antimicrobial agents of some mercury-sensitive and mercury-resistant strains of Gram-negative bacteria

The sensitivity and resistance of some Gram-negative mercury (Hg²⁺)-sensitive and-resistant strains to chemotherapeutic agents and to disinfectants and preservatives are described.Escherichia coli andPseudomonas aeruginosa strains harboring plasmid pUB 1351 [pUB 367:Tn 501] andE. coli bearing R100-1 were resistant to inorganic mercury and to various antibiotics, but were not more resistant to organic mercury and other preservatives and disinfectants than plasmidless strains.     

Effects of fungicides on Aspergillus fumigatus

Aspergillus fumigatus was the most frequently isolated thermophilous fungus from green leaf surfaces. The application of fungicides significantly reduced the frequency of its occurrence there. A. fumigatus was relatively tolerant to fungicides. On Captan-, Thiram-, and Verdasan-treated leaves, A. fumigatus constituted 66%–80% of the total number of isolates obtained at 45°C from each treatment while Dicloran did not depress the percentages. At 45°C, A. fumigatus was found to be strongly cellulolytic with a slow rate of radial extension on YpSs agar and rapid rate of mycelial growth in Czapek Dox liquid medium. Increasing concentrations of all four fungicides reduced or prevented growth, sporulation, starch depletion and cellulose clearing of A. fumigatus. The fungus could tolerate higher concentrations of HgCl₂ than of Verdasan. 0.5 g/ml of the four fungicides altered the rates of mycelial growth but not the maximum amount of mycelial dry weight attained.