The role of encapsulation in the pathogenesis of anaerobic gram-positive cocci

The pathogenicity of 22 anaerobic and facultative Gram-positive cocci (AFGPC) was investigated by inoculating them into mice and determining their ability to cause subcutaneous abscesses. Only 11 heavily encapsulated isolates (greater than 50% of the cells were encapsulated) induced abscesses. However, when the other 11 isolates were injected with Bacteroides sp. or facultative and aerobic bacteria, abscesses were formed in 8 of the 11 combinations. The AFGPC recovered from the mixed infections contained many encapsulated cells. Encapsulation also occurred in cocci injected with capsular material or with Formalin-killed cells of Klebsiella pneumoniae or capsule-positive Bacteroides sp. After acquisition of capsules, these strains could induce abscesses on reinoculation in mice.     

Yolk polypeptide gene expression in Minute Drosophila females

Minutes have been considered for some time to be mutant at the sites of synthesis of some components of the protein synthetic apparatus. To study the hypothetical relationship between Minutes and suboptimal translation, a group of abundant proteins, the yolk polypeptides, was assayed in outcrossed females bearing M(3)w, M(3)h ^y , or M(1)n mutations. Recently emerged Minute females contained a lower amount of yolk polypeptides, in both ovarian and nonovarian tissues, than their non-Minute sisters. This low level correlated with the lower abundance of cytoplasmic RNA in Minutes compared to control females. By 1 week of age, both M(3)w and their non-Minute sibs contained the same amount of yolk polypeptides and the corresponding mRNA. The double heterozygote, ap ⁴/+;M(3)w/+, did not differ in yolk polypeptide content from control flies. M(3)w females demonstrated reduced fecundity during the period of low yolk polypeptide content but gradually increased egg deposition as yolk polypeptide levels rose. These results suggest that the low protein levels are due to the slower maturation of M(3)w, and not to less efficient translation machinery.This work was supported by the NSERC (Canada) and a Queen's University ARC grant.     

Comparison of glucokinase in C3H/He and C58 mice that differ in their hepatic activity

Partially purified preparations of the hepatic glucokinase from C3H/He and C58 inbred mice have been used to explore the molecular basis for the observed twofold difference in activity between the strains. The single codominant gene that appears to regulate activity, the alleles of which are designated Gk^a and Gk^b, respectively, for the two strains, could represent a structural gene change. This now seems unlikely because the mouse enzyme, although showing small differences from rat glucokinase, appeared to be identical in the two strains with respect to thermal stability, electrophoretic mobility in agarose gels, and kinetic properties such as the apparent K _m values for MgATP^2– and glucose and the unique cooperative interaction with the latter substrate. The enzymes also reacted identically in a range of immunological tests (double-diffusion, immunoelectrophoresis, immune precipitation and immune inhibition assays) and ELISA immune inhibition assays indicated that the twofold difference in activity was due to a similar difference in antigenically active enzyme. Genetic control over the physiologically significant regulation of enzyme amount is therefore probable.This work has been supported in part by a grant from the British Diabetic Association and a Training Studentship to PAJ from the Medical Research Council (U.K.).     

The skeleton of early Eocene Cantius, oldest lemuriform primate

A recently discovered partial skeleton of the adapid Cantius trigonodus from the early Eocene Willwood Formation of the Bighorn Basin, Wyoming, documents substantial new information about the anatomy of the oldest lemuriform primates. It is very similar in all features to its descendant, middle Eocene Notharctus, and both exhibit numerous resemblances to certain extant Malagasy lemurs, particularly Lepilemur, Propithecus, Lemur, and Hapalemur griseus. Like these forms, Cantius had relatively long hind limbs and short forelimbs. Forelimb traits (prominent brachialis flange of the humerus, well-developed olecranon process of the ulna, and strong shafts of the ulna and radius) suggest active use of the forelimbs in progression. Specializations in the hind limb (e.g., expanded articular surface of the femoral head, narrow and elevated patellar trochlea and prominent lateral trochlear ridge, posteriorly oriented femoral and tibial condyles, narrow and elongate talus, and hallucal metatarsal with prominent peroneal tubercle) indicate capabilities for leaping and for powerful grasping with an opposable hallux. Cantius was presumably primitive in having a relatively long ischium and much more distal inferior tibial tuberosity than most extant lemurs--traits suggesting that powerful extension of the thigh and flexion at the knee were important in its locomotion and posture. We interpret Cantius as an active arboreal quadruped with a propensity for leaping. The existence of this skeletal structure in one of the oldest primates of modern aspect suggests that it represents the primitive lemuriform morphology.     

The thermodynamics of bovine and porcine insulin and proinsulin association determined by concentration difference spectroscopy

Difference spectroscopy was used to determine the equilibrium constants and thermodynamic parameters for the monomer-dimer association of bovine and porcine insulin and bovine proinsulin at pH 2.0 and 7.0. At pH 2 delta G degree 25, delta S degree, and delta H degree for dimerization of bovine insulin were found to be -6.6 kcal/mol, -18 cal/mol-deg, and -12 kcal/mol, respectively. Porcine insulin behaved similarly to bovine insulin in its dimerization properties in that delta G degree 25, delta S degree, and delta H degree were found to be -6.8 kcal/mol, -14 cal/mol-deg, and -11 kcal/mol, respectively. At pH 7 delta G degree 25, delta S degree, and delta H degree for dimerization of bovine insulin were found to be -7.2 kcal/mol, -16 cal/mol/deg, and -12 kcal/mol, respectively. At pH 7.0 delta G degree 25, delta S degree, and delta H degree for dimerization of porcine insulin were -6.7 kcal/mol, -11.6 cal/mol-deg, and -10 kcal/mol, respectively. The similarity in the thermodynamic parameters of both insulin species at the different pH's suggests that there are minimal structural changes at the monomer-monomer contact site over this pH range. The dimerization of both insulin species is under enthalpic control. This may suggest that the formation of the insulin dimer is not driven by hydrophobic bonding but, rather, is driven by the formation between subunits of four hydrogen bonds in an apolar environment. At pH 2 delta G degree 25, delta S degree, and delta H degree for dimerization of bovine proinsulin were found to be -5.3 kcal/mol, -26 cal/mol-deg, and -13 kcal/mol, respectively. At pH 7 delta G degree 25, delta S degree, and delta H degree for dimerization of proinsulin were -5.9 kcal/mol, -4.2 cal/mol-deg, and -7.2 kcal/mol, respectively. Although the presence of the C-peptide on proinsulin does not drastically affect the overall free energy change of dimer formation (as compared to insulin), the other thermodynamic parameters are rather drastically altered. This may be because of electrostatic interactions of groups on the C-peptide with groups on the B-chain which are near the subunit contact site in the insulin dimer.     

Hormonal modulation of responses to thymus-independent and thymus-dependent antigens in autoimmune NZB/W mice

Previous work suggested that gonadal steroids influence immunity through the thymus, but the mechanisms were unclear. To investigate the effects of these hormones on immune responses to T1 and TD antigens in autoimmune mice, we studied hybrid NZB/W mice and the nonautoimmune DBA/2 strain. Mice castrated at 14 days of age were implanted with Silastic capsules releasing, in adults, physiologic levels of E2 in males or Te in females. Sham-operated controls received empty capsules. Splenic PFC were quantified 4 to 5 days after challenge with the TI2 antigen TNP-Ficoll, the TI1 antigen TNP-LPS, or the TD antigen SRBC. Young castrated NZB/W males implanted with E2 had striking enhancement of IgM responses to TNP-Ficoll when compared to castrated Te-treated females and comparable sham-operated controls of both sexes. E2 also stimulated responses to TNP-LPS. In response to challenge with SRBC, young E2-treated NZB/W males had a consistent trend to increased IgM PFC, and the stimulatory effect of E2 on IgG plaques was variable. Physiologic doses of Te had no consistent effect on responses in young mice. In old female NZB/W mice, Te caused PFC response after immunization with TNP-Ficoll to resemble age-matched NZB/W males. As sham-operated NZB/W females grew older, PFC responses to SRBC fell. This age-related phenomenon was delayed, however, in female castrates implanted with Te. In contrast, Te clearly suppressed responses to TNP-LPS. Implantation of E2 did not alter responses to TNP-Ficoll, TNP-LPS, or SRBC in nonautoimmune DBA/2 males. This finding suggested that exogenous E2 given in physiologic doses did not influence immunologic responsiveness in a normal strain to the degree seen in hormone-sensitive NZB/W mice. It was concluded that E2 enhanced responses to a variety of exogenous antigens in autoimmune NZB/W mice. The most consistent E2-induced increase in PFC response was observed with TI antigens, suggesting that E2 exerted its effects on B cells or Ts.     

Co-expression of an epitope on human free kappa-light chains and on a cytoplasmic component in activated T cells

K-1-21 is a murine monoclonal antibody that reacts with human kappa-light chains in free form but not when they are associated with immunoglobulin heavy chains. K-1-21 was unexpectedly shown to bind to a determinant, STA (Sezary T cell antigen), detected by immunofluorescence in the cytoplasm but not on the surface of Sezary T cells isolated from peripheral blood (4/4 cases) and in Sezary T cells from lymph node and bone marrow (one patient). STA was detected in F2/F7, CCRF-CEM, Molt-4, and CCRF-HSB (four human T ALL cell lines), in JURKAT (a human T cell leukemia line), and in MLA144 (a Gibbon T cell lymphoma line). It also occurred in Leu-3a+ antigen-specific T cell clones (6/6 tested). Moreover, although STA was absent from freshly isolated normal T cells, its expression could be evoked in E+ cells from peripheral blood by in vitro culture with phytohemagglutinin. Thus, STA appears to be a cytoplasmic marker for activated T cells. Cytoplasmic inhibition immunofluorescence studies indicated that K-1-21 binding to STA in Sezary cells or T cell lines was inhibited by preincubation of the K-1-21 antibody with purified kappa-Bence Jones protein. STA from radiolabeled MLA144 cell lysates was immunoprecipitated by K-1-21 and was identified on polyacrylamide gel electrophoresis under reducing conditions as a protein of m.w. 57,000. Additional experiments are underway to define the molecular basis of the interesting cross-reactivity between a determinant in T cells and the K-1-21 reactive epitope on free kappa-light chains.     

Complementation of a pKM101 derivative that decreases resistance to UV killing but increases susceptibility to mutagenesis

The drug resistance plasmid pKM101 makes Escherichia coli resistant to the lethal effects of ultraviolet (UV) irradiation and more susceptible to mutagenesis by a variety of agents. The plasmid operon responsible for increasing mutagenesis has been termed mucAB (Mutagenesis, UV and chemical). We have isolated a derivative of pKM101 called pGW1975 which makes cells more sensitive to killing by UV but which retains the ability of pKM101 to increase susceptibility to methyl methanesulfonate (MMS) mutagenesis. pGW1975 increases UV mutagenesis less than pKM101 in a uvrA⁺ strain but more than pKM101 in a uvrA⁻ strain. muc⁻ point and insertion mutants of pKM101 and pGW1975 complement to restore the plasmid-mediated: (i) ability to reactivate UV-irradiated phage, (ii) resistance to killing by UV, and (iii) level of susceptibility to UV mutagenesis. We have identified a 2.0 kb region of pKM101 which is responsible for the complementation and which maps counterclockwise of mucAB.     

On the population dynamics and ecology of the shrimp species (Crustacea,Decapoda, Natantia) in the Central Amazonian river Tarumã-Mirim

Summary Collections over four years in the habitat of submerged litter show that shrimps are abundant the year round. Mean densities vary from 5–45 animals/m² of litter habitat. Finegrained density distribution within litter sites is highly clumped, but coarse-grained distribution in any given month between litter sites along the river is grosso-modo random.Density and species distribution are a function of the annual cycles of inundations. Of the five species (of a total of seven in the area) that were found to be breeding in the litter habitat it could be established that reproduction is restricted to the period of rising and highest water levels. Reproduction is low in all species, namely below 20 eggs per egg batch with essentially a single generation per year.Breeding ecology in relation to the litter habitat is briefly discussed.This project was supported jointly by the CNPq (Brasilian Research Council), by the OAS (Organization of the American States) and by the SUFRAMA (Financing body of local government)     

Chemical composition of whole plant and grain and yield of nutrients in grain of five barley cultivars

Summary twenty seven field experiments were conducted to determine if there were differences between five barley cultivars in their ability to utilize soil nutrients. There were significant differences among cultivars in yield of grain and in concentration of all macro and micro nutrients examined in both the whole plant and grain.Gateway ranked the highest for the concentration of Na, Mn, and Cu in the whole plant and was among the cultivars with highest concentration of Ca, Fe, and Zn. Centennial had generally the lowest concentration of all the nutrients determined in the whole plant. For the concentrations of Na, Mg, and Cu in grain Gateway ranked highest, but ranked third for the concentrations of K, Ca, Fe, Mn, and Zn in grain. Galt had the highest K and Mg concentration and lowest Mn, Cu and Zn concentration in grain. Except for K concentration in grain, Centennial had the lowest concentrations of all other cationic nutrients in grain.Yield of grain rather than nutrient concentration was the most important criteria in determining the ranking of nutrient yields per hectare. Because of its high grain yield, Bonanza produced the largest yield of micronutrient cations and was second to Galt in production of macronutrient cations, although it was lowest in macronutrient cation concentration. Similarly, Bonanza and Galt had the lowest protein concentration, but produced the highest yield of protein per hectare.The implications for animal nutrition of different levels of nutrients between cultivars are discussed.